The average age of an adult class is 40 years

The average age of an adult class is 40 years. 12 new students with an avg age of 34years join the class. Therefore decreasing the average by 4 years. Find what was the original average age of the class?

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 #70435