$\left\{\begin{matrix}x\leq \frac{40}{lo}\text{, }&\left(l>0\text{ and }o<0\right)\text{ or }\left(o>0\text{ and }l<0\right)\\x=\frac{40}{lo}\text{, }&o\neq 0\text{ and }l\neq 0\\x\geq \frac{40}{lo}\text{, }&\left(l<0\text{ and }o<0\right)\text{ or }\left(l>0\text{ and }o>0\right)\end{matrix}\right.$

$\left\{\begin{matrix}o\leq \frac{40}{lx}\text{, }&\left(l>0\text{ and }x<0\right)\text{ or }\left(x>0\text{ and }l<0\right)\\o=\frac{40}{lx}\text{, }&x\neq 0\text{ and }l\neq 0\\o\geq \frac{40}{lx}\text{, }&\left(l<0\text{ and }x<0\right)\text{ or }\left(l>0\text{ and }x>0\right)\end{matrix}\right.$