## College Algebra (10th Edition)

$x=\dfrac{a+b}{c}$
Multiply $x$ to both sides of the equation to obtain: $\begin{array}{ccc} \require{cancel} &x\left(\dfrac{a}{x} + \dfrac{b}{x}\right)&=&c(x) \\&\cancel{x}\left(\dfrac{a}{\cancel{x}}\right) + \cancel{x}\left(\dfrac{b}{\cancel{x}}\right)&=&cx \\&a+b&=&cx \end{array}$ Divide $c$ to both sides of the equation to obtain: $\dfrac{a+b}{c} =x$