If you had a system that led to an impossible equation, such as $\displaystyle{0}={1}\usepackage{cmbright}\Huge\$ , then there would be no solution. However, if you substitute $\displaystyle{3}{x}+{2}\usepackage{cmbright}\Huge\$ for y in the second equation and then simplify, you will end up with the equation $\displaystyle{8}={8}\usepackage{cmbright}\Huge\$ . This equation is true regardless of the value of x.