Answer
The required equation is $x=k\frac{{{z}^{3}}}{y}$ and the value of $y$ is $k\frac{{{z}^{3}}}{x}$.
Work Step by Step
As, the value of $x$ varies directly as $ {{z}^{3}}$ and inversely as $y$ ,
$x=k\frac{{{z}^{3}}}{y}$
Where $k$ is a constant.
Now, solve the above equation for $y$.
$y=k\frac{{{z}^{3}}}{x}$
