## Precalculus (6th Edition) Blitzer

The required equation is $x=k\frac{yz}{\sqrt{w}}$ and value of $y$ is $\frac{x\sqrt{w}}{kz}$.
As the value of $x$ varies jointly as $y$ and $z$ and inversely as $\ \sqrt{w}$ , we have $x=k\frac{yz}{\sqrt{w}}$ Where $k$ is a constant Now, solve the above equation for $y$. Divide $x=k\frac{yz}{\sqrt{w}}$ by $\frac{\sqrt{w}}{kz}$ , and we have $y=\frac{x\sqrt{w}}{kz}$