2-14. John buys a TV for 600 from Jean. John agrees to pay for the TV by making a cash down payment of 50, then paying 100 every four months for one year (i.e. three payments of 100), and finally making a single payment 16 months after the purchase (i.e. four months after the last payment of 100). (a) Find the amount of the final payment if John is charged interest at an effective rate of 12% per year. (b) Find the effective annual interest rate if John's final payment is 350