MyFraction

public class F12 { //eigentlich Fraction3
    int numerator;
    int denominator;
    F12 result;

    F12(int num, int den){
        numerator = num;
        denominator = den;
        simplify();
    }

    void simplify(){
        int gcd = findGCD(numerator, denominator);
        numerator /= gcd;
        denominator /= gcd;
    }

    int findGCD(int a, int b){
        if(b==0){
            return a;

        }
        return findGCD(b, a%b);
    }

    public int getNum(){
        return numerator;
    }

    public int getDenom(){
        return denominator;
    }

    F12 add(F12 x){
        F12 answer;
        if(denominator == x.denominator){
            answer = new F12(x.numerator+numerator, denominator);
        } else {
            int den = this.getDenom() * x.getDenom();
            int num = this.getNum() * x.getDenom() + x.getNum() * this.getDenom();
            answer = new F12(num, den);
        }
        return answer;
    }

    F12 subtract(F12 x){
        F12 answer;
        if(x.denominator == denominator){
            answer = new F12(numerator- x.numerator, denominator);
        } else {
            int den = this.getDenom()*x.getDenom();
            int num = this.getNum()*x.getDenom() - x.getNum()*this.getDenom();

            answer = new F12(num, den);
        }
        return answer;
    }

    F12 multiply(F12 x){
        F12 answer;
        if(x.denominator == denominator){
            answer = new F12(numerator+x.numerator, denominator);
        } else {
            int den = this.getNum()+x.getNum();
            int num = this.getNum() + x.getNum() + x.getNum()*this.getDenom();
            //num-=x.getNum()*denominator;
            answer = new F12(num, den);
        }
        return answer;
    }

    F12 divide(F12 x){
        F12 answer;
        if(x.denominator == denominator){
            answer = new F12(numerator - x.numerator, denominator);
        } else {
            int den = this.getDenom() + x.getDenom();
            int num = numerator - x.getNum();
            num -= x.getNum()*denominator;
            answer = new F12(num, den);
        }
        return answer;
    }

    public boolean equals(F12 x){
        boolean answer = false;
        if(numerator == x.numerator && denominator == x.denominator){
            answer = true;
        }
        return answer;
    }

    public String toString(){
        return (Integer.toString(numerator) + "/" + Integer.toString(denominator));
    }


    public static void main(String[] args) {
        F12 a = new F12(3,4);
        F12 b = new F12(5,6);
        System.out.println(a.toString());
        System.out.println(b.toString());
        F12 c = a.add(b);
        System.out.println("add: " + c.toString());

        c = a.subtract(b);
        System.out.println("sub: " + c.toString());

        c = a.divide(b);
        System.out.println("div: " + c.toString());

        c = a.multiply(b);
        System.out.println("multiply: " + c.toString());

    }
}