Use a test point in each region. For example, $\displaystyle{\left({10},{30}\right)}\usepackage{cmbright}\Huge\$ makes $\displaystyle{s}+{2}{m}>{100}\usepackage{cmbright}\Huge\$ false, so region 1 is not shaded. The test point $\displaystyle{\left({10},{60}\right)}\usepackage{cmbright}\Huge\$ makes $\displaystyle{s}+{m}>{100}\usepackage{cmbright}\Huge\$ false, so region 2 is not shaded. Finally, $\displaystyle{\left({10},{100}\right)}\usepackage{cmbright}\Huge\$ makes both inequalities true, so region 3 is shaded.