Chapter 3 - Polynomial and Rational Functions - Exercise Set 3.7 - Page 430: 20

$ x=\displaystyle \frac{kz}{(y+w)}$ $y=\displaystyle \frac{kz}{x}-w$

$x$ varies directly as $z:\qquad x=kz$ $x$ varies inversely as $(y+w) :\displaystyle \qquad x=\frac{k}{(y+w)}$ Combined (jointly): $\displaystyle \qquad x=\frac{kz}{(y+w)}$ Solving for $y,$ $x=\displaystyle \frac{kz}{(y+w)}\qquad/\times(y+w)$ $x(y+w)=kz\qquad/\div x$ $y+w=\displaystyle \frac{kz}{x}\qquad/-w$ $y=\displaystyle \frac{kz}{x}-w$