Working alone, Mary can pave a driveway in 3 hours and Hillary…

Working alone, Mary can pave a driveway in 3 hours and Hillary can pave the same driveway in 6 hours. When they work together, Mary thrives on teamwork so her rate increases by 10%, but Hillary becomes distracted and her rate decreases by 20%. If they both work together, how many hours will it take to pave the driveway?

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 #16582