Salma wants to buy a new house but needs money for the down payment. Her parents agree to lend her money at an annual rate of 4%, charged as simple interest. They lend her $4000 for 2 years. She makes no payments except the one at the end of that time.

(a) How much total interest will Salma have to pay?

(b) What will the total repayment amount be (including interest)?