*20. You have some extra cash this month and you are considering putting it toward your car loan. Your interest rate is 7%, your loan payments are $600 per month, and you have 36 months left on your loan. If you pay an additional $1000 with your next regu- lar $600 payment (due in one month), how much will it reduce the amount of time left to pay off your loan? *21. You have an outstanding student loan with required payments of $500 per month for the next four years. The interest rate on the loan is 9% APR (monthly). You are considering making an extra payment of $100 today (i.e., you will pay an extra $100 that you are not required to pay). If you are required to continue to make payments of $500 per month until the loan is paid off, what is the amount of your final payment? What effective rate of return (expressed as an APR with monthly compounding) have you earned on the $100? *22. Consider again the setting of Problem