what kind of formula to use. we doing it old fashion, no exel

Tim needs a new car while he attends college for the next three years. The car he would like has an MRSP of $15,000. A local dealer can get him a three-year loan with a 7% interest rate if Tim can make a $1,500 down payment. The same dealer offers the same car for lease with a money factor of 0.00271 and a residual value of 75%. The lease requires an additional fee of $1,250 to cover Tim's security deposit and the acquisition and documentation fees for the car. Tim is looking to drive the car home with the smallest monthly payment. Should he buy or lease the car. Show work