## University Calculus: Early Transcendentals (3rd Edition)

$37.5$ miles per hour
Let $t_1$ be the time is taken for the forward trip: Then, $t_1=\dfrac{150}{30}=5 hrs$ Let $t_2$ be the time is taken for the return trip: Then, $t_2=\dfrac{150}{50}=3 hrs$ Now, $t_1+t_2=8 hrs$ Total distance =150 +150=300 miles Thus, the total time taken is: $T=\dfrac{300}{8}=37.5$ miles per hour