Need help creating formula for this question/answer:

You plan to purchase a house for $400,000 and you will make a 20% down payment. You are evaluating two mortgages a 30-year fixed mortgage at 3.34% and a 15-year fixed mortgage at 2.45%. Your goal is to have a monthly payment that fits within your budget. a) Which mortgage will give you the lowest monthly payment? What will that payment be? How much less will this be than the other monthly mortgage payment? b) Assuming you take the full term of the mortgage, which mortgage will result in you paying the most interest? What will that interest be?