$$\left. \begin{array} { l } { \quad 4 x - y = - 8 } \\ { y = 4 x + 8 } \end{array} \right.$$
$x=\frac{y-8}{4}$
$y\in \mathrm{C}$
$x=\frac{y-8}{4}$
$y\in \mathrm{R}$
