Suppose you are buying your first house for $400,000, and are making an $80,000 down payment. You have arranged to finance the remaining amount with a 15-year, monthly payment, amortized mortgage at a 3.60% nominal interest rate. What will your equal monthly payments be? For the 120th payment, what is the break down between interest payment vs. principal payment? what is remaining balance after 25 years with 300 monthly payments?