You may have subtracted 10 from $\displaystyle{3}{y}-{7}\usepackage{cmbright}\Huge\$ as your first step, and then solved $\displaystyle{3}{y}-{17}=-{5}\usepackage{cmbright}\Huge\$ and $\displaystyle{3}{y}-{17}={5}\usepackage{cmbright}\Huge\$ . This means you are subtracting before finding the absolute value, and that is not the correct order of operations. You need to add 10 to both sides first, and then solve $\displaystyle{3}{y}-{7}={5}\usepackage{cmbright}\Huge\$ and $\displaystyle{3}{y}-{7}=-{5}\usepackage{cmbright}\Huge\$ .