$$5x \times { y }^{ -1 } = \frac{ z }{ 2.5 }$$
$x=\frac{2yz}{25}$
$y\neq 0$
$\left\{\begin{matrix}\\y\neq 0\text{, }&\text{unconditionally}\\y=\frac{25x}{2z}\text{, }&x\neq 0\text{ and }z\neq 0\end{matrix}\right.$
