You may have switched the x-coordinate and the y-coordinate when solving. This ordered pair is not a solution to the equation $\displaystyle{x}-{y}={2}\usepackage{cmbright}\Huge\$ because $\displaystyle{\left({0}\right)}-{\left({2}\right)}={2}\usepackage{cmbright}\Huge\$ , or $\displaystyle-{2}={2}\usepackage{cmbright}\Huge\$ , is not a true statement.