You are taking out a single-payment loan that uses the simple interest method to compute the finance charge. You need to figure out what your payment will be when the loan comes due. The equation to calculate the finance charge is: F = P r t + X 1 / In the equation, F, is the finance charge for the loan. What are the other values? P is the amount of the loan. payback rate of interest. principal monthly annual t is the term of the loan in r is the stated months. years