Starting at the point $\displaystyle{\left(-{3},{1}\right)}\usepackage{cmbright}\Huge\$ , move one unit down and then two units to the right to get to the point $\displaystyle{\left(-{1},{0}\right)}\usepackage{cmbright}\Huge\$ . The rise is $\displaystyle-{1}\usepackage{cmbright}\Huge\$ and the run is 2.

$\displaystyle{S}{l}{o}{p}{e}=\frac{{{r}{i}{s}{e}}}{{{r}{u}{n}}}=\frac{{-{1}}}{{2}}=-\frac{{1}}{{2}}\usepackage{cmbright}\Huge\$