Problem
You buy a House of $50,000.00. Today, you put a down payment of 20% and borrow a fixed rate mortgage of $40,000.00 with monthly payments annual interest rate of 3.5% and 30 years. After 5 years market interest rate goes up to 6.5%. How much money will you make in book from the mortgage if you continue to pay the monthly mortgages for the next 25 years in the market interest rate will stay the same as 6.5%.