Suppose a borrower and lender agree to a 30-year, monthly payment loan in which the interest rate is fixed for the first 3 years at 7% and will change to 6% at the beginning of year 4. The loan is fully amortizing in all years. What will the payment be in month 63? How much principal will be contained in that payment?

An excel spreadsheet showing functions in the amortization schedule would be appreciated. Thank you.