An amortized loan made at an effective rate of 4% is to be repaid by n level end-of-year payments. If the principal repaid in the 20th payment is 480.

(a) If the amount of principal paid in the 10th payment is (in two decimals).

(b) If the principal repayment in the 20th payment is 76% of the payment, the term of the loan is n = years (in integer).