/**
* @param Rational $value
* @return Rational
*/
public function subtract(Rational $value) : Rational
{
$coef = new static(integer(-1), integer(1));
return $this->add($value->multiply($coef));
}
/**
* @param Rational $value
* @return Rational
*/
public function subtract(Rational $value) : Rational
{
$coef = new static(integer(-1), integer(1));
return $this->add($value->multiply($coef));
}