Elkford Logging's bank will fix the interest rate on a $60,000 loan at 4.2% compounded monthly for the first four-year term of an eight-year amortization period. Monthly payments are required on the loan.

a. If the prevailing interest rate on four-year loans at the beginning of the second term is 6% compounded monthly, what will be the monthly payments for the last four years?

b. What will be the interest portion of the 23rd payment?

c. Calculate the principal portion of the 53rd payment.