## College Algebra 7th Edition

$r=\frac{d}{t}$ $t=\frac{d}{r}$
We solve for $r$ by dividing by $t$: $\displaystyle \frac{d}{t}=\frac{rt}{t}$ $r=\frac{d}{t}$ We solve for $t$ by dividing by $r$: $\displaystyle \frac{d}{r}=\frac{rt}{r}$ $t=\frac{d}{r}$