Show all your work in solving the problems. You don't need to provide formulas but do need to show all calculator keystrokes to get full credit for your answers. (60 points total -15 points each) 3. Your parents bought a home 15 years ago and have a mortgage rate of 9% on their $150,000 mortgage with a 30 -year term. Today they could refinance into a new 15 year mortgage at a rate of 7%. Refinancing will cost $3500. a. Should they refinance if they plan to stay in the home for an additional 15 years? b. Should they refinance if they may only stay in the home for 5 more years