[tex](\stackrel{x_1}{1}~,~\stackrel{y_1}{-1})\qquad (\stackrel{x_2}{-8}~,~\stackrel{y_2}{-7}) \\\\\\ \stackrel{slope}{m}\implies \cfrac{\stackrel{rise} {\stackrel{y_2}{-7}-\stackrel{y1}{(-1)}}}{\underset{run} {\underset{x_2}{-8}-\underset{x_1}{1}}}\implies \cfrac{-7+1}{-9}\implies \cfrac{-6}{-9}\implies \cfrac{-2}{-3}\implies \cfrac{2}{3}[/tex]
