When $\displaystyle{x}={1}\usepackage{cmbright}\Huge\$ , $\displaystyle{10}-{4}{x}={10}-{4}\cdot{1}={10}-{4}={6}\usepackage{cmbright}\Huge\$ .

When $\displaystyle{x}={2}\usepackage{cmbright}\Huge\$ , $\displaystyle{10}-{4}{x}={10}-{4}\cdot{2}={10}-{8}={2}\usepackage{cmbright}\Huge\$ .