Chapter 3 - Equations and Problem Solving - 3.2 - Equations and Problem Solving - Problem Set 3.2 - Page 106: 47

t = $\frac{A}{Pr}$ - $\frac{1}{r}$

Using the properties of equality we obtain: $A = P + Prt $ Subtract P from both sides $A - P = Prt $ Divide both sides by Pr $\frac{A}{Pr}$ - $\frac{P}{Pr}$ = $\frac{Prt}{Pr}$ $\frac{A}{Pr}$ - $\frac{1}{r}$ = t