You forgot to reverse the inequality signs when you divided all parts of the inequality by $\displaystyle-{5}\usepackage{cmbright}\Huge\$ . Also, this answer makes no sense, because it says that $\displaystyle{k}\usepackage{cmbright}\Huge\$ is less than $\displaystyle-{8}\usepackage{cmbright}\Huge\$ , but more than $\displaystyle-{1}\usepackage{cmbright}\Huge\$ .