You may have correctly combined like terms to get $\displaystyle{2}{y}+{8}={64}\usepackage{cmbright}\Huge\$ . However, at this point you may have added 8 to the right side thinking that this would isolate the variable term. To do this you would need to subtract 8 from both sides of the equation. The correct answer is $\displaystyle{y}={28}\usepackage{cmbright}\Huge\$ .