If you borrow $220,000 at an APR of 3.5 for 25 years, you will pay $1,101.37 per month. If you borrow the same amount at the same APR for 30 years, you will pay $987.90 per month. 

a. What is the total interest paid on the 25-year mortgage?
b. What is the total interest paid on the 30-year mortgage?
c. How much more interest is paid on the 30-year mortgage? Round to the nearest dollar.
d. If you can afford the difference in monthly payments, you can take out the 25-year mortgage and save all the interest from part c. What is the difference between the monthly payments of the two different mortgages? Round to the nearest dollar.