Chapter 3 - Polynomial and Rational Functions - Exercise Set 3.7 - Page 430: 12

$x=kyz^{2}$ $y=\displaystyle \frac{x}{kz^{2}}$

$x$ varies directly as $y:\qquad x=ky$ $x$ varies directly as $z^{2}:\qquad x=kz^{2}$ Combined (jointly): $\qquad x=kyz^{2}$ Solving for $y,$ divide both sides by ($kz^{2})$ $\displaystyle \frac{x}{kz^{2}}=y$