A can do a piece of work in 20days, and B can…

A can do a piece of work in 20days, and B can do it in 15days. How long will they take if both work together?

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 #36506