Eric borrowed money last year to buy a new car for his part-time consulting work. The loan is a 3-year loan with 36 monthly payments. Due to his bad credit history, the loan he got is with a 12% annual interest rate compounded monthly. The monthly payment for Eric is $500/month. (a) If Eric saved some money with this extra consulting work in the past year and is considering paying off this high interest rate loan, how much does Eric owe right after he paid the 15th payment at the end of 15th month? (b) If Eric can use $10,000 of his savings to purchase a device now (at the end of 15 months) that can boost his consulting work income by 10%, should he purchase this device to boost his income instead of paying off his car loan, why