src/main/java/Rational/Rational.java

@@ -41,9 +41,9 @@ public class Rational {
 
     //  COMPLETED - Instance method: this + other
     public Rational add(Rational other) {
-        int newNumerator = this.numerator * other.denominator + other.numerator * this.denominator;
-        int newDenominator = this.denominator * other.denominator;
-        return new Rational(newNumerator, newDenominator);
+        int newNum = this.numerator * other.denominator + other.numerator * this.denominator;
+        int newDenom = this.denominator * other.denominator;
+        return new Rational(newNum, newDenom);
     }
 
     //  COMPLETED - Static method: r1 + r2
@@ -54,42 +54,53 @@ public class Rational {
     // TODO: Instance method - this - other
     // Formula: a/b - c/d = (a*d - c*b) / (b*d)
     public Rational subtract(Rational other) {
-        // YOUR CODE HERE
-        return null; // Remove this line when implemented
+        int newNum = this.numerator * other.numerator - other.numerator * this.denominator;
+        int newDenom = other.numerator * this.denominator;
+        return new Rational(newNum, newDenom);
     }
 
     // TODO: Static method - r1 - r2
     public static Rational subtract(Rational r1, Rational r2) {
-        // YOUR CODE HERE
-        return null; // Remove this line when implemented
+        int newNum = r1.numerator * r2.denominator - r2.numerator * r1.denominator;
+        int newDenom = r1.denominator * r2.denominator;
+        return new Rational(newNum, newDenom);
     }
 
     // TODO: Instance method - this * other
     // Formula: (a/b) * (c/d) = (a*c) / (b*d)
     public Rational multiply(Rational other) {
-        // YOUR CODE HERE
-        return null; // Remove this line when implemented
+        int newNum = this.numerator * other.numerator;
+        int newDenom = this.denominator * other.denominator;
+        return new Rational(newNum, newDenom);
     }
 
     // TODO: Static method - r1 * r2
     public static Rational multiply(Rational r1, Rational r2) {
-        // YOUR CODE HERE
-        return null; // Remove this line when implemented
+        int newNum = r1.numerator * r2.numerator;
+        int newDenom = r1.denominator * r2.denominator;
+        return new Rational(newNum, newDenom);
     }
 
     // TODO: Instance method - this / other
     // Formula: (a/b) ÷ (c/d) = (a*d) / (b*c)
     public Rational divide(Rational other) {
-        // YOUR CODE HERE
-        // HINT: Division is multiplication by reciprocal
-        // Don't forget to check if other.numerator is zero!
-        return null; // Remove this line when implemented
+        if (other.numerator == 0){
+            throw new ArithmeticException("Cannot divide by zero");
+        }
+        int newNum = this.numerator * other.denominator;
+        int newDenom = this.denominator * other.numerator;
+        return new Rational(newNum, newDenom);
     }
 
     // TODO: Static method - r1 / r2
     public static Rational divide(Rational r1, Rational r2) {
-        // YOUR CODE HERE
-        return null; // Remove this line when implemented
+        if (r2.numerator == 0){
+            throw new ArithmeticException("Cannot divide by zero");
+        }
+        int newNum = r1.numerator * r2.denominator;
+        int newDenom = r1.denominator * r2.numerator;
+
+        return new Rational(newNum, newDenom);
     }
 
     //  PROVIDED - String representation