A loan of $9,000 is repaid by payments of $645 at the end of every six months. Interest is 9% compounded semi-annually. (a) How many payments are required to repay the debt? (b) What is the size of the final payment? (a) The number of payments is (Round up to the nearest whole number.) (b) The size of the final payment is $ (Round the final answer to the nearest cent as needed. Round all intermediate values to six decimal places as needed.)