I am trying to help my son with the problem below. The answer posted does not even begin to solve the problem as the interest rate used was the annual rate and not the monthly rate. I can calculate the payment amount but not by using the formulas discussed in chapter 1 of A First Course in Mathematical Modeling by Frank R Giordano Can someone help with this. Your current credit card balance is $12,000 with a current rate of 19.9% per year. Interest is charged monthly. Determine what monthly payment p will pay off the card in a. Two years, assuming no new charges b. Four years, assuming no new charges