## College Algebra (6th Edition)

$x=\displaystyle \frac{kyz}{w^{2}}$ $y=\displaystyle \frac{xw^{2}}{kz}$
$x$ varies directly as $y:\qquad x=ky$ $x$ varies directly as $z:\qquad x=kz$ $x$ varies inversely as $w^{2} :\displaystyle \qquad x=\frac{k}{w^{2}}$ Combined (jointly): $\displaystyle \qquad x=\frac{kyz}{w^{2}}$ Solving for $y,$ (multiply both sides with $\displaystyle \frac{w^{2}}{kz})$ $\displaystyle \frac{xw^{2}}{kz}=y$