The average age of 20 students in a class is 5years

The average age of 20 students in a class is 5years. If teacher's age is also included then average increases 1year then find the teacher's age?

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 #10087