DIRE NEED OF HELP PROGRAM WORTH 2/3 OF MY GRADE

So the program is suppose to be able add and subtract fractions and then reduce it. I figured out how to do that until i realized if i put in a negative number it doesn't work anymore here's the object class

public class packet5exercise10bobject 
{

public void ReadFraction()

{

  KeyboardReader reader=new KeyboardReader();

int num,denom,num1,denom1,orignum,origdenom,orignum1,origdenom1;

System.out.println("Enter the numerator");
        num= reader.readInt();
        orignum=num;
        System.out.println("Enter the denominator");
        denom= reader.readInt();
        origdenom=denom;
        System.out.println("Enter the 2nd numerator");
        num1= reader.readInt();
        orignum1=num1;
        System.out.println("Enter the 2nd denominator");
        denom1= reader.readInt();
        origdenom1=denom1;
        AddFraction(num, denom, num1, denom1);
    }
    public void AddFraction(int num,int denom,int num1,int denom1)
    {
        int nume,denome;
        nume= (num*denom1)+(num1*denom);
        denome= denom*denom1;
        Reduce(nume, denome);
    }
    public void Reduce(int num, int denom)
    {
        int origdenom,factor,
        orignum=num;
        origdenom=denom;
        while (num!=denom)
        {
            if (num>denom)
            {
                num= num-denom;
            }
            else
            {
                denom=denom-num;
            }
        }
        factor=num;
        orignum=orignum/factor;
        origdenom=origdenom/factor;
        DisplayTime(orignum, origdenom);
    }
    public void DisplayTime(int orignum, int origdenom)

    {
        System.out.println("The reduced fraction is "+orignum+"/"+origdenom);
    }

}