[tex]\bf (\stackrel{x_1}{5}~,~\stackrel{y_1}{-5})\qquad (\stackrel{x_2}{-1}~,~\stackrel{y_2}{-5}) \\\\\\ \stackrel{slope}{m}\implies \cfrac{\stackrel{rise} {\stackrel{y_2}{-5}-\stackrel{y1}{(-5)}}}{\underset{run} {\underset{x_2}{-1}-\underset{x_1}{5}}}\implies \cfrac{-5+5}{-6}\implies \cfrac{0}{-6}\implies 0[/tex]
