30 men can do a work in 40 days

30 men can do a work in 40 days. When should 12 men leave the work so that the entire work is completed in 40 days after they leave the work?

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 #59891