Check the picture below.
[tex]\bf (\stackrel{x_1}{-3}~,~\stackrel{y_1}{-5})\qquad (\stackrel{x_2}{9}~,~\stackrel{y_2}{3}) \\\\\\ \stackrel{slope}{m}\implies \cfrac{\stackrel{rise} {\stackrel{y_2}{3}-\stackrel{y1}{(-5)}}}{\underset{run} {\underset{x_2}{9}-\underset{x_1}{(-3)}}}\implies \cfrac{3+5}{9+3}\implies \cfrac{8}{12}\implies \cfrac{2}{3}[/tex]
