Julie drives to her sister’s house and back

Julie drives to her sister’s house and back. She takes the exact same route both ways. On the trip out she drives an average speed of 80 miles per hour. On the trip back she drives an average speed of 40 miles per hour. What is her approximate average speed for the round trip in miles per hour?

AQuA-RAT — Algebra Question Answering with Rationales (Ling et al., DeepMind, 2017) · train #71819