Write a BankAccount class that includes an instance variable for the balance, and methods for interacting with that balance: getBalance, deposit, and withdraw.
Write a subclass SavingsAccount that inherits from BankAccount, and includes a double instance variable interestRate, where the value is given as a percent (ie. 1.5 represents 0.015). This class should have an addInterest method that uses the interest rate for the account to increase the balance by the correct amount.
Then write a CheckingAccount subclass that also inherits from BankAccount. This class charges a fee of 0.25 dollars every time money is withdrawn from the account.