What is the monthly payment on these two mortgages and what is the total amount of interest paid over the life of the mortgage.

1)15 years or 180 months = N, i =4.25%, PV or mortgage is $300,000.What is your monthly payment?Then multiply your monthly payment by the number of months you pay it and subtract the original mortgage value.That product t is the value of the interest you paid over the life of the loan.

2) 30 years or 360 months = N, i = 4.5% (longer term loans have slightly higher interest rates), PV or mortgage is $300,000?Same exercise as above.