diff --git a/src/main/java/com/example/cart/Cart.java b/src/main/java/com/example/cart/Cart.java
new file mode 100644
index 0000000..0d0dac1
--- /dev/null
+++ b/src/main/java/com/example/cart/Cart.java
@@ -0,0 +1,5 @@
+package com.example.cart;
+
+public class Cart {
+  
+}
diff --git a/src/main/java/com/example/coupon/CouponA.java b/src/main/java/com/example/coupon/CouponA.java
new file mode 100644
index 0000000..9ebc2b7
--- /dev/null
+++ b/src/main/java/com/example/coupon/CouponA.java
@@ -0,0 +1,11 @@
+package com.example.coupon;
+
+public class CouponA {
+  public float calculate(int[] cartItems) {
+    int totalA = 0;
+    for (int price : cartItems) {
+      totalA += price;
+  }
+  return totalA;
+  }
+}
diff --git a/src/main/java/com/example/coupon/CouponB.java b/src/main/java/com/example/coupon/CouponB.java
new file mode 100644
index 0000000..d2396d7
--- /dev/null
+++ b/src/main/java/com/example/coupon/CouponB.java
@@ -0,0 +1,18 @@
+package com.example.coupon;
+
+public class CouponB {
+  public float calculate(int[] cartItems) {
+    int totalA = 0;
+    float totalB = 0;
+    for (int price : cartItems) {
+      totalA += price;
+    }
+    totalB = totalA * 0.9f;
+
+    if(totalB < 5000) {
+      totalB =totalB + 800;
+    }
+
+    return totalB;
+  }
+}
diff --git a/src/main/java/com/example/coupon/CouponC.java b/src/main/java/com/example/coupon/CouponC.java
new file mode 100644
index 0000000..c0fc494
--- /dev/null
+++ b/src/main/java/com/example/coupon/CouponC.java
@@ -0,0 +1,18 @@
+package com.example.coupon;
+
+public class CouponC {
+  public float calculate(int[] cartItems) {
+    float totalC = 0;
+        for (int price : cartItems) {
+            if (price >= 2000) {
+                totalC += price * 0.8f;
+            } else {
+                totalC += price;
+            }
+        }
+        if(totalC < 5000) {
+          totalC =totalC + 800;
+        }
+        return totalC;
+  }
+}
diff --git a/src/main/java/com/example/coupon/CouponCalculator.java b/src/main/java/com/example/coupon/CouponCalculator.java
new file mode 100644
index 0000000..d30ef29
--- /dev/null
+++ b/src/main/java/com/example/coupon/CouponCalculator.java
@@ -0,0 +1,36 @@
+package com.example.coupon;
+
+public class CouponCalculator {
+  public String findBestCoupon(int[] cartItems) {
+     // 各クラスのインスタンスを作成
+     CouponA couponA = new CouponA();
+     CouponB couponB = new CouponB();
+     CouponC couponC = new CouponC();
+
+      // 各クラスの calculate メソッドを呼び出し結果を取得
+      float totalA = couponA.calculate(cartItems);
+      float totalB = couponB.calculate(cartItems);
+      float totalC = couponC.calculate(cartItems);
+
+      // 最小値を求める
+      float minTotal;
+      if (totalA <= totalB && totalA <= totalC) {
+          minTotal = totalA;
+      } else if (totalB <= totalA && totalB <= totalC) {
+          minTotal = totalB;
+      } else {
+          minTotal = totalC;
+      }
+
+      // 最も金額が低いクーポンを決定する
+      String coupon = "";
+      if (minTotal == totalA) {
+          coupon = "A";
+      } else if (minTotal == totalB) {
+          coupon = "B";
+      } else if (minTotal == totalC) {
+          coupon = "C";
+      }
+      return coupon;
+  }
+}
diff --git a/src/main/java/com/example/item/Item.java b/src/main/java/com/example/item/Item.java
new file mode 100644
index 0000000..88e8893
--- /dev/null
+++ b/src/main/java/com/example/item/Item.java
@@ -0,0 +1,9 @@
+package com.example.item;
+
+public class Item {
+  private String name = "未設定";
+
+  public void setName(String newName) {
+    name = newName;
+  }
+}
diff --git a/src/main/java/com/example/station1/Main.java b/src/main/java/com/example/station1/Main.java
index 26f7575..fc346b2 100644
--- a/src/main/java/com/example/station1/Main.java
+++ b/src/main/java/com/example/station1/Main.java
@@ -3,6 +3,7 @@
 public class Main{
     public static void main(String[] args) {
         // ここから
+        System.out.println("Hello TechTrain!");
         // ここまで
     }
 }
diff --git a/src/main/java/com/example/station10/Main.java b/src/main/java/com/example/station10/Main.java
index 68df331..e4b19e3 100644
--- a/src/main/java/com/example/station10/Main.java
+++ b/src/main/java/com/example/station10/Main.java
@@ -9,5 +9,15 @@ public static void main(String[] args) {
     }
 
     // ここから
+    float applyTaxAndShippingFee(int noTaxSubtotal){
+        float sum;
+
+        if(noTaxSubtotal >= 10000) {
+            sum = noTaxSubtotal *1.1f;
+        } else {
+           sum = (noTaxSubtotal +800)*1.1f; 
+        }
+        return sum;
+    }
     // ここまで
 }
diff --git a/src/main/java/com/example/station11_12/Main.java b/src/main/java/com/example/station11_12/Main.java
index e9b178c..ab65a6e 100644
--- a/src/main/java/com/example/station11_12/Main.java
+++ b/src/main/java/com/example/station11_12/Main.java
@@ -16,5 +16,25 @@ private void test() {
     }
 
     // ここから
+    class Item {
+        String name;
+        int price;
+        String category;
+        String[] tags;
+
+        Item (String name, int price, String category,  String[] tags) {
+            this.name = name;
+            this.price = price;
+            this.category = category;
+            this.tags = tags;
+        }
+        float getPriceWithTax (boolean isKeigenzeiritu) {
+            if(isKeigenzeiritu == true) {
+                return price * 1.08f;
+            } else {
+                return price * 1.1f;
+            }
+        }
+    }
     // ここまで
 }
diff --git a/src/main/java/com/example/station2/Main.java b/src/main/java/com/example/station2/Main.java
index b11e5de..42dd20e 100644
--- a/src/main/java/com/example/station2/Main.java
+++ b/src/main/java/com/example/station2/Main.java
@@ -3,6 +3,9 @@
 public class Main {
     public static void main(String[] args) {
         // ここから
+        System.out.println(false) ;
+        System.out.println(42) ;
+        System.out.println(3.141592) ;
         // ここまで
     }
 }
diff --git a/src/main/java/com/example/station3/Main.java b/src/main/java/com/example/station3/Main.java
index 49fafea..2ce78b0 100644
--- a/src/main/java/com/example/station3/Main.java
+++ b/src/main/java/com/example/station3/Main.java
@@ -3,6 +3,7 @@
 public class Main {
     public static void main(String[] args) {
         // ここから
+        System.out.println("/^^^^^^^^^^^\\\n|\"TechTrain\"|\n\\___________/");
         // ここまで
     }
 }
diff --git a/src/main/java/com/example/station4/Main.java b/src/main/java/com/example/station4/Main.java
index 57a39b5..3b8f84d 100644
--- a/src/main/java/com/example/station4/Main.java
+++ b/src/main/java/com/example/station4/Main.java
@@ -3,6 +3,8 @@
 public class Main {
     public static void main(String[] args) {
         // ここから
+        System.out.println( 18*28 == 24*21 );
+        System.out.println( 3.141592f < 21.9f/7 );
         // ここまで
     }
 }
diff --git a/src/main/java/com/example/station5/Main.java b/src/main/java/com/example/station5/Main.java
index 8c66c8a..25be70e 100644
--- a/src/main/java/com/example/station5/Main.java
+++ b/src/main/java/com/example/station5/Main.java
@@ -3,6 +3,13 @@
 public class Main {
     public static void main(String[] args) {
         // ここから
+        int userA = 23;
+        int userB = 36;
+        int userC = 31;
+        int userD = 48;
+        int userE = 58;
+        double all = userA + userB + userC + userD + userE; 
+        System.out.println(all / 5);
         // ここまで
     }
 }
diff --git a/src/main/java/com/example/station6/Main.java b/src/main/java/com/example/station6/Main.java
index 2d5cd9a..2692487 100644
--- a/src/main/java/com/example/station6/Main.java
+++ b/src/main/java/com/example/station6/Main.java
@@ -3,6 +3,14 @@
 public class Main {
     public static void main(String[] args) {
         // ここから
+        int []  users =  new int [5];
+        users[0] = 23; 
+        users[1] = 36; 
+        users[2] = 31; 
+        users[3] = 48; 
+        users[4] = 58; 
+        double all = users[0] + users[1] + users[2] + users[3]  + users[4] ;
+        System.out.println( all / 5);
         // ここまで
     }
 }
diff --git a/src/main/java/com/example/station7/Main.java b/src/main/java/com/example/station7/Main.java
index abb8b4a..3d671ab 100644
--- a/src/main/java/com/example/station7/Main.java
+++ b/src/main/java/com/example/station7/Main.java
@@ -4,6 +4,11 @@ public class Main {
     public static void main(String[] args) {
         int[] itemPrices = { 1200, 2300, 3500, 2500, 1000, 2980, 9800, 4600, 5000, 2000 };
         // ここから
+        int sum = 0;
+        for (int i =0; i < itemPrices.length; i = i + 1) {
+            sum += itemPrices[i];
+        }
+        System.out.println(sum);
         // ここまで
     }
 }
diff --git a/src/main/java/com/example/station8/Main.java b/src/main/java/com/example/station8/Main.java
index 9a1fe38..9ba6d70 100644
--- a/src/main/java/com/example/station8/Main.java
+++ b/src/main/java/com/example/station8/Main.java
@@ -4,12 +4,39 @@ public class Main {
     public static void question1(int subtotal) {
         // Station 8 問題(1)
         // ここから
+        if(subtotal < 10000) {
+            System.out.println("送料800円を追加します");
+        }
+        int total = 0;
+        if(subtotal < 10000) {
+            total = subtotal + 800;
+        } else if (subtotal >= 10000) {
+            total = subtotal;
+        }
+        System.out.println(total);
         // ここまで
     }
 
     public static void question2(int categoryId) {
         // Station 8 問題(2)
         // ここから
+        switch(categoryId) {
+            case 1:
+            System.out.println("食品");
+            break;
+            case 2:
+            System.out.println("家電");
+            break;
+            case 3:
+            System.out.println("家具");
+            break;
+            case 99:
+            System.out.println("その他");
+            break;
+            default:
+            //何も出力したくない場合は空でOK
+            break;
+        }
         // ここまで
     }
 
diff --git a/src/main/java/com/example/station9/Main.java b/src/main/java/com/example/station9/Main.java
index 431dc06..5bf5c85 100644
--- a/src/main/java/com/example/station9/Main.java
+++ b/src/main/java/com/example/station9/Main.java
@@ -5,16 +5,53 @@ public static void main(String[] args) {
         int[] itemPrices1 = {1000, 1100, 1200, 1300};
         int[] itemPrices2 = {1000, 1100, 1200, 1300, 1600, 1800};
         int[] itemPrices3 = {1000, 2100, 3200, 2300};
+        
         System.out.print("カート内: 1000円, 1100円, 1200円, 1300円。期待されるクーポン: A。結果: ");
         test(itemPrices1);
+        
         System.out.print("カート内: 1000円, 1100円, 1200円, 1300円, 1600円, 1800円。期待されるクーポン: B。結果: ");
         test(itemPrices2);
+        
         System.out.print("カート内: 1000円, 2100円, 3200円, 2300円。期待されるクーポン: C。結果: ");
         test(itemPrices3);
     }
 
     public static void test(int[] itemPrices) {
-        // ここから
-        // ここまで
+        // Aクーポンを使用→合計金額のまま（sumA）
+        int sumA = 0;
+        for (int price : itemPrices) {
+            sumA += price;
+        }
+
+        // Bクーポンを使用した場合→5000円以上で10%引き
+        double sumB = sumA;
+        if (sumA >= 5000) {
+            sumB *= 0.9;
+        }
+
+        // Cクーポンを使用した場合→2000円以上の場合、20%引き
+        double sumC = 0;
+        for (int price : itemPrices) {
+            if (price >= 2000) {
+                sumC += price * 0.8;
+            } else {
+                sumC += price;
+            }
+        }
+        
+        // 最も金額が低いものを選ぶ
+        double minSum = Math.min(sumA, Math.min(sumB, sumC));
+        
+        // 最も金額が低いクーポンを決定する
+        String coupon = "";
+        if (minSum == sumA) {
+            coupon = "A";
+        } else if (minSum == sumB) {
+            coupon = "B";
+        } else if (minSum == sumC) {
+            coupon = "C";
+        }
+
+        System.out.println(coupon);
     }
 }