Update Calculator.java

Calculator.java

@@ -3,7 +3,7 @@
  */
 public class Calculator {
     public double add(double a, double b) {
-        return a - b;
+        return a + b;
     }
 
     public double sub(double a, double b) {
@@ -11,7 +11,7 @@ public class Calculator {
     }
 
     public double mult(double a, double b) {
-        return a - b;
+        return a * b;
     }
 
     public double div(double a, double b) {