## Thinking Mathematically (6th Edition)

$t=\dfrac{A-P}{Pr}$
Distribute $P$ to obtain: $A=P+Prt$ Subtract $P$ on both sides to obtain: $A-P=Prt$ Divide $Pr$ on both sides to obtain: $\dfrac{A-P}{Pr} = \dfrac{Prt}{Pr}$ Cancel the common factors to obtain: $\require{cancel} \dfrac{A-P}{Pr} = \dfrac{\cancel{Pr}t}{\cancel{P r}} \\\dfrac{A-P}{Pr} = t$