Check the picture below, since the points are the points of a line, we can always get the slope of a linear by simply using two points, hmmm say (8,6) and (12,8)
[tex]\bf (\stackrel{x_1}{8}~,~\stackrel{y_1}{6})\qquad (\stackrel{x_2}{12}~,~\stackrel{y_2}{8}) ~\hfill \stackrel{slope}{m}\implies \cfrac{\stackrel{rise} {\stackrel{y_2}{8}-\stackrel{y1}{6}}}{\underset{run} {\underset{x_2}{12}-\underset{x_1}{8}}}\implies \cfrac{2}{4}\implies \cfrac{1}{2}[/tex]
