+62 Miles drives the same path to and from work. If he averages 50 miles per hour on the way to work and 60 miles per hour on the way from work, what is the average speed of his entire commute?
+37153 time at 50 mph = d / 50
time at 60 mph = d/60
total distance = 2d
distance / time = average
2d / ( d/50 + d/60)
2 / (1/50 + 1/60) = 54.5 m/hr
