diff --git a/syamauchi/src/C020.java b/syamauchi/src/C020.java
new file mode 100644
index 0000000000000000000000000000000000000000..446b00ad210cf4808610973914363a467df75e78
--- /dev/null
+++ b/syamauchi/src/C020.java
@@ -0,0 +1,41 @@
+package src;
+
+import java.math.BigDecimal;
+import java.util.Scanner;
+
+public class C020 {
+  static BigDecimal PERCENTAGE = new BigDecimal("100");
+  private final String foodWeight;
+  private final String saleFoodRatio;
+  private final String saleSideDishRatio;
+
+  public C020(final String foodWeight, final String saleFoodRatio, final String saleSideDishRatio) {
+    this.foodWeight = foodWeight;
+    this.saleFoodRatio = saleFoodRatio;
+    this.saleSideDishRatio = saleSideDishRatio;
+  }
+
+  public static void main(String[] args) {
+    final Scanner sc = new Scanner(System.in);
+    final C020 food = new C020(sc.next(), sc.next(), sc.next());
+    System.out.println(food.calcUnsold());
+    sc.close();
+  }
+
+  // 誤差ができるのが嫌なのでBigDecimalを使用
+  public float calcUnsold() {
+    final BigDecimal foodWeight = new BigDecimal(this.foodWeight);
+    final BigDecimal saleFoodRatio = new BigDecimal(this.saleFoodRatio);
+    final BigDecimal saleSideDishRatio = new BigDecimal(this.saleSideDishRatio);
+
+    final BigDecimal percentageSaleFood = saleFoodRatio.divide(PERCENTAGE);
+
+    // food - food * percentageSaleFood
+    final BigDecimal unsold = foodWeight.subtract(foodWeight.multiply(percentageSaleFood));
+    final BigDecimal percentageSaleSideDish = saleSideDishRatio.divide(PERCENTAGE);
+    // unsold - unsold * percentageSideDish
+    final BigDecimal allUnsold = unsold.subtract(unsold.multiply(percentageSaleSideDish));
+    //
+    return (allUnsold.floatValue());
+  }
+}
diff --git a/syamauchi/test/C020Test.java b/syamauchi/test/C020Test.java
new file mode 100644
index 0000000000000000000000000000000000000000..b50d31fea86d8c552bdac1e8d430c6fe2cfd4f55
--- /dev/null
+++ b/syamauchi/test/C020Test.java
@@ -0,0 +1,63 @@
+package test;
+
+import static org.hamcrest.CoreMatchers.*;
+import static org.hamcrest.MatcherAssert.*;
+import org.junit.Test;
+import src.C020;
+
+public class C020Test {
+
+  @Test
+  public void 残り物の量を取得するテスト1() {
+    C020 sut = new C020("1", "80", "40");
+    float expected = (float) 0.12;
+    float actual = sut.calcUnsold();
+
+    assertThat(actual, is(expected));
+  }
+
+  @Test
+  public void 残り物の量を取得するテスト2() {
+    C020 sut = new C020("10", "31", "52");
+    float expected = (float) 3.312;
+    float actual = sut.calcUnsold();
+
+    assertThat(actual, is(expected));
+  }
+
+  @Test
+  public void 残り物の量を取得するテスト3() {
+    C020 sut = new C020("1", "0", "0");
+    float expected = (float) 1;
+    float actual = sut.calcUnsold();
+
+    assertThat(actual, is(expected));
+  }
+
+  @Test
+  public void 残り物の量を取得するテスト4() {
+    C020 sut = new C020("1000", "100", "0");
+    float expected = (float) 0;
+    float actual = sut.calcUnsold();
+
+    assertThat(actual, is(expected));
+  }
+
+  @Test
+  public void 残り物の量を取得するテスト5() {
+    C020 sut = new C020("1000", "0", "0");
+    float expected = (float) 1000;
+    float actual = sut.calcUnsold();
+
+    assertThat(actual, is(expected));
+  }
+
+  @Test
+  public void 残り物の量を取得するテスト6() {
+    C020 sut = new C020("1", "0", "100");
+    float expected = (float) 0;
+    float actual = sut.calcUnsold();
+
+    assertThat(actual, is(expected));
+  }
+}