$$\frac{ 1 }{ x } + \frac{ 1 }{ y } - \frac{ 1 }{ z } =5$$
$x=-\frac{yz}{z-y-5yz}$
$y\neq 0\text{ and }z\neq 0\text{ and }\left(z=-\frac{1}{5}\text{ or }y\neq \frac{z}{5z+1}\right)$
$y=-\frac{xz}{z-x-5xz}$
$z\neq 0\text{ and }x\neq 0\text{ and }\left(z=-\frac{1}{5}\text{ or }x\neq \frac{z}{5z+1}\right)$