Given an abstract class, RentableDwelling, containing:

a private double instance variable rentPerUnit

a public constructor accepting a double used to initialize rentPerUnit

a public method getRentPerUnit that returns the value of rentPerUnit

a public abstract method getRentalIncome that returns a double

Write a public $($non$-$abstract$)$ subclass, ApartmentHouse, containing:

a private int instance variable, numberOfApartments

a public constructor accepting a double, passed to the superclass constructor, and an int used to initialize numberOfApartments

a public method getRentalIncome that calculates the product of numberOfApartments and the rent per unit. getRentalIncome returns a double