Question 12
Consider the following simultaneous equations:
$$\begin{aligned}xy^2+xyz&=91,\\xyz-y^2z&=72,\end{aligned}$$
where $x,y,z$ are positive integers. Find the maximum value of $xz$.
$$\begin{aligned}xy^2+xyz&=91,\\xyz-y^2z&=72,\end{aligned}$$
where $x,y,z$ are positive integers. Find the maximum value of $xz$.