Substitute 4 for x and $\displaystyle-{3}\usepackage{cmbright}\Huge\$ for y in each equation.

$\displaystyle{4}-{2}{\left(-{3}\right)}=-{2}\usepackage{cmbright}\Huge\$ $\displaystyle-{3}-{4}=-{7}\usepackage{cmbright}\Huge\$

$\displaystyle{4}+{6}=-{2}\usepackage{cmbright}\Huge\$ $\displaystyle-{7}=-{7}\usepackage{cmbright}\Huge\$

$\displaystyle{10}=-{2}\usepackage{cmbright}\Huge\$

Only one equation is true, so $\displaystyle{\left({4},-{3}\right)}\usepackage{cmbright}\Huge\$ is not a solution to the system.

$\displaystyle{4}-{2}{\left(-{3}\right)}=-{2}\usepackage{cmbright}\Huge\$	$\displaystyle-{3}-{4}=-{7}\usepackage{cmbright}\Huge\$
$\displaystyle{4}+{6}=-{2}\usepackage{cmbright}\Huge\$	$\displaystyle-{7}=-{7}\usepackage{cmbright}\Huge\$
$\displaystyle{10}=-{2}\usepackage{cmbright}\Huge\$