7. Brando borrows 40,000. He repays the loan with n end of year payments with the annual effective interest rate being 7%. For each of the first n - 1 payments, the payment is twice the interest then due. The final payment X is the balance due at that time. Suppose the final payment cannot exceed 4000. (a) Find the smallest possible value for n. (b) If the n is chosen to be the smallest possible value, what is X