Practice solving and using literal equations. Tahmar knows the formula for simple interest is I = Prt, where I represents the simple interest on an amount of money, P, for t years at r rate. She transforms the equation to isolate P : P = P : P equals StartFraction I Over r t EndFraction.. Using this formula, what is the amount of money, P, that will generate $20 at a 5% interest rate over 5 years?