subtract method
Implementation
Fraction subtract(Fraction otherParsed) {
if (denominator == otherParsed.denominator) {
return Fraction(numerator - otherParsed.numerator,
denominator: denominator);
}
return Fraction(
(numerator * otherParsed.denominator) -
(otherParsed.numerator * denominator),
denominator: denominator * otherParsed.denominator);
}