You may have tried to apply the Addition Property of Equality by adding $\displaystyle\frac{{1}}{{3}}\usepackage{cmbright}\Huge\$ , instead of multiplying both sides of the equation by $\displaystyle-{3}\usepackage{cmbright}\Huge\$ . Adding $\displaystyle\frac{{1}}{{3}}\usepackage{cmbright}\Huge\$ to $\displaystyle{\left(-\frac{{1}}{{3}}\right)}{x}\usepackage{cmbright}\Huge\$ will not leave you with x, and you must do the same thing to both sides.