Add 3 to both sides, and then divide by $\displaystyle-{2}\usepackage{cmbright}\Huge\$ :

$\displaystyle-{2}{s}-{3}+{3}\le-{7}+{3}\usepackage{cmbright}\Huge\$ or $\displaystyle-{2}{s}\le-{4}\usepackage{cmbright}\Huge\$

$\displaystyle\frac{{-{2}{s}}}{{-{{2}}}}\ge\frac{{-{4}}}{{-{{2}}}}\usepackage{cmbright}\Huge\$ or $\displaystyle{s}\ge{2}\usepackage{cmbright}\Huge\$