I need help with a few questions with forumlas

5. A college student is buying a new car, which costs $18,000 plus 7% sales tax. The title, license, and registration fees are $600. The dealer offers her a financing program that starts with a monthly payment of $300, and each successive payment will increase by a constant dollar amounty. the dealer offers to finance 80% of the car's price for 48 months at a nominal interest rate of 12% per year, compounded monthly. (a) How much is the constant amount y? (b) How much is the 48th payment? 6. A newly graduated engineer bought furniture for S900 from a store. Monthly payments for 1year will be made. Interest is compounded at a nominal rate of 12%. Build a table that shows the balance due, principal payment, and the interest payment for each payment. What is the monthly payment