/// <summary>
/// The Subtract method subtracts a Fraction from the NonNegativeFraction
/// If the passed Fraction would cause the NonNegativeFraction to be negative, throws an ArgumentOutOfRangeException
/// </summary>
/// <param name="fraction">Fraction to subtract</param>
protected override void Subtract(Fraction fraction)
{
fraction = fraction.Copy();
fraction *= -1;
Add(fraction);
}