Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

$r=fw$
$\bf{\text{Solution Outline:}}$ To solve the given equation, $w=\dfrac{r}{f}$ for $r ,$ use the properties of equality to isolate the variable. $\bf{\text{Solution Details:}}$ Using the properties of equality to isolate the variable, the equation above is equivalent to \begin{array}{l}\require{cancel} w=\dfrac{r}{f} \\\\ f\cdot w=f\cdot \dfrac{r}{f} \\\\ fw=r \\\\ r=fw .\end{array}