[tex](\stackrel{x_1}{12}~,~\stackrel{y_1}{-7})\qquad (\stackrel{x_2}{4}~,~\stackrel{y_2}{5}) \\\\\\ \stackrel{slope}{m}\implies \cfrac{\stackrel{rise} {\stackrel{y_2}{5}-\stackrel{y1}{(-7)}}}{\underset{run} {\underset{x_2}{4}-\underset{x_1}{12}}}\implies \cfrac{5+7}{-8}\implies \cfrac{12}{-8}\implies -\cfrac{3}{2}[/tex]
