Substituting $\displaystyle-{10}\usepackage{cmbright}\Huge\$ for y gives $\displaystyle{0}+{7}+{\left(-{10}\right)}\usepackage{cmbright}\Huge\$ , which is equal to $\displaystyle{7}+{\left(-{10}\right)}\usepackage{cmbright}\Huge\$ , or $\displaystyle-{3}\usepackage{cmbright}\Huge\$ .