You may have simplified $\displaystyle{{\left({5}-{9}\right)}}^{{2}}\usepackage{cmbright}\Huge\$ incorrectly by squaring the 9 and then subtracting $\displaystyle{5}-{81}\usepackage{cmbright}\Huge\$ . You must simplify inside parentheses before doing other operations. So this part of the expression would first simplify to $\displaystyle{{\left(-{4}\right)}}^{{2}}\usepackage{cmbright}\Huge\$ .