Untitled

 public Rational multi(Rational r)
        {
            return new Rational (this.num * r.num, this.den * r.den);
            
        }
        public Rational dev(Rational r)
        {
            return new Rational ( this.num *= r.den, this.den * r.num);
            
        }
        public Rational add(Rational r)
        {
            return new Rational (this.num = (this.num * r.den) + (r.num * this.den), this.den *= r.den);
           
        }
        public Rational minus(Rational r)
        {
            return new Rational (this.num = (this.num * r.den) - (r.num * this.den),  this.den *= r.den);