Rebecca purchased a house for $500,000. She made a down payment of 25.00% of the value of the house and received a mortgage for the rest of the amount at 6.12% compounded semi-annually amortized over 25 years. The interest rate was fixed for a 6 year period.

a. Calculate the monthly payment amount.

b. Calculate the principal balance at the end of the 6 year term.

c. Calculate the monthly payment amount if the mortgage was renewed for another 6 years at 4.52% compounded semi-annually?