A pipe can fill a cistern in 20 minutes whereas the cistern…

A pipe can fill a cistern in 20 minutes whereas the cistern when fill can be emptied by a leak in 60 minutes. When both pipes are opened, find when the cistern will be full?

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 #21823