a) Using the Rational interface, implement a class called RationalNumber that uses integers internally. The numerator and denominator should never change value. public interface Rational { public float getQuotient(); //computes the quotient public Rational add(Rational other) //this + other public Rational divide(Rational other) //this / other } //TODO: complete this class. public class RationalNumber implements Rational {

b) How is the class you created above immutable? Be specific. What are advantages and disadvantages of it being immutable?