For the past n days, the average (arithmetic mean) daily production at…

For the past n days, the average (arithmetic mean) daily production at a company was 40 units. If today's production of 90 units raises the average to 45 units per day, what is the value of n ?

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 #21060