Shelly rows 4m kilometers downstream at 6x kilometers per hour

Shelly rows 4m kilometers downstream at 6x kilometers per hour. Then she turns around and rows m/6 kilometers upstream at 2x kilometers per hour. What is Shelly's average rowing speed in kilometers per hour during the entire journey?

AQuA-RAT — Algebra Question Answering with Rationales (Ling et al., DeepMind, 2017) · train #61631