Average of money that group of 4 friends pay for rent each…

Average of money that group of 4 friends pay for rent each month is $800.After one persons rent is increased by 20% the new mean is $870.What was original rent of friend whose rent is increased?

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 #18512