The interest rate for the first three years of an $86,000 mortgage is 7.4% compounded semiannually. Monthly payments are based on a 20-year amortization. Suppose a $4500 prepayment is made at the end of the sixteenth month.

a.	How much will the amortization period be shortened?
	The amortization period will be shortened by months.

b.	What will be the principal balance at the end of the three-year term? (Round your answer to the nearest cent.)