During his morning commute to work in rush hour traffic, Justin's average speed was 30 mi/h. During his afternoon commute back home along the same route, his average speed was 60 mi/h. What was his average speed for the entire round trip?
Avg speed over the same distance = 2 * product of the rates / ( sum of the rates) =
2 (30)(60) / ( 30 + 60)
I'll leave the rest for you.......