You may have correctly combined like terms and simplified to get $\displaystyle{4}{y}={32}\usepackage{cmbright}\Huge\$ . However, at this point you may have multiplied the right side by 4 instead of dividing both sides by 4. Multiplying $\displaystyle{4}{y}\usepackage{cmbright}\Huge\$ by 4 will not isolate the variable, and you must do the same thing to both sides. The correct answer is $\displaystyle{y}={8}\usepackage{cmbright}\Huge\$ .