In a 100-mile trip, the first 20 miles were completed at 40…

In a 100-mile trip, the first 20 miles were completed at 40 mph. If the average speed for the whole trip was 50 mph, what was the average speed in the last 80 miles?

This problem repeats another one in the library (at most with different numbers), so it's left out of browsing.

AQuA-RAT — Algebra Question Answering with Rationales (Ling et al., DeepMind, 2017) · train #36141