public static Fraction Subtract(Fraction frac1, Fraction frac2)
 {
     return(!((Fraction)null != frac1) || !((Fraction)null != frac2) ? (Fraction)null : Fraction.Add(frac1, -frac2));
 }
 public static Fraction operator -(Fraction frac1, int iNo)
 {
     return(!((Fraction)null != frac1) ? (Fraction)null : Fraction.Add(frac1, -new Fraction((long)iNo)));
 }
 public static Fraction operator -(Fraction frac1, double dbl)
 {
     return(!((Fraction)null != frac1) ? (Fraction)null : Fraction.Add(frac1, -Fraction.ToFraction(dbl)));
 }
 public static Fraction operator -(Fraction frac1, Fraction frac2)
 {
     return(!((Fraction)null != frac1) || !((Fraction)null != frac2) ? (Fraction)null : Fraction.Add(frac1, -frac2));
 }