the slope or average rate of change for the trip from the graph is just rise/run. Now, let's take a look at those values to get it
[tex]\bf slope\implies \cfrac{rise}{run}\implies \cfrac{distance}{time(mins)}\implies \cfrac{9}{45}=\cfrac{8}{40}=\cfrac{7}{35}=\cfrac{6}{30}=\cfrac{5}{25}\implies \stackrel{\stackrel{slope}{\downarrow }}{\cfrac{1}{5}}[/tex]
so the slope of it is 1/5, 2 hours is 120 minutes, what would be the distance value on 120 minutes?
[tex]\bf \cfrac{distance}{time(mins)}=\stackrel{slope}{\cfrac{1}{5}}\qquad \qquad \cfrac{\stackrel{miles}{d}}{\underset{minutes}{120}}=\cfrac{1}{5}\implies d=\cfrac{120}{5}\implies d=24[/tex]
