Answer
14 mph
Work Step by Step
Recall that velocity is equal to change in distance over change in time. We call t the time it takes Abu. Thus, we obtain:
$\frac{72}{t+2} = \frac{ 56}{t} -2 $
We create common denominators and solve for t:
$ \frac{72t}{t(t+2)} = \frac{56(t+2)}{t(t+2)} + \frac{-2t(t+2)}{t(t+2)}$
Since the denominators are the same, we cancel them out and solve. (Recall, t cannot be negative.)
$ 0 = -2t^2 -20t + 112 \\ 2(t-4)(t+14) \\ t =4 $
Thus, we find the velocity:
$v_{Abu} = 56/4 =14$ mph
