code: public Rational divide(Rational value)
      {
          return new Rational(numerator * value.getDenominator(),
                              denominator * value.getNumerator());
      }
docs: Divide this rational by the specified value and return the result as a new
  object (also a Rational).
  @param value The amount to divide by.
  @return A new rational value that is the result of dividing this value by
  the specified value.