to get the slope of any straight line, we only need two points off of it, let's use the ones in the picture below.
[tex](\stackrel{x_1}{8}~,~\stackrel{y_1}{25})\qquad (\stackrel{x_2}{24}~,~\stackrel{y_2}{35}) ~\hfill \stackrel{slope}{m}\implies \cfrac{\stackrel{rise} {\stackrel{y_2}{35}-\stackrel{y1}{25}}}{\underset{run} {\underset{x_2}{24}-\underset{x_1}{8}}}\implies \cfrac{10}{16}\implies \cfrac{5}{8}[/tex]
