$$\frac{x}{a}+b=c$$
$\left\{\begin{matrix}a=-\frac{x}{b-c}\text{, }&x\neq 0\text{ and }b\neq c\\a\neq 0\text{, }&b=c\text{ and }x=0\end{matrix}\right.$
$b=c-\frac{x}{a}$
$a\neq 0$
