During the first stage of the division process, when you should have been subtracting, you may have added $\displaystyle-{8}{x}\usepackage{cmbright}\Huge\$ and $\displaystyle-{8}{x}\usepackage{cmbright}\Huge\$ . This would have given you $\displaystyle-{16}{x}\usepackage{cmbright}\Huge\$ left over for the next stage to divide by $\displaystyle{x}-{8}\usepackage{cmbright}\Huge\$ . Make sure that you distribute the minus sign when you get to the steps involving subtraction.