$$3a+b=-4r; -2a+b=-32$$
$r\in \mathrm{C}$
$a=\frac{32-4r}{5}$
$b=\frac{-8r-96}{5}$
$r\in \mathrm{R}$
$a=\frac{32-4r}{5}$
$b=\frac{-8r-96}{5}$
