Substitute 8 for x and 2 for y.

$\displaystyle{8}-{3}{\left({2}\right)}={2}\usepackage{cmbright}\Huge\$	$\displaystyle{2}={8}+{6}\usepackage{cmbright}\Huge\$
$\displaystyle{8}-{6}={2}\usepackage{cmbright}\Huge\$	$\displaystyle{2}={14}\usepackage{cmbright}\Huge\$ False
$\displaystyle{2}={2}\usepackage{cmbright}\Huge\$ True

Since the ordered pair does not make both equations true, it is not a solution to the system.