A city had 400 migrants in the year 2000

A city had 400 migrants in the year 2000. Since then, The number of migrants in a countrythe city has doubled every 3 years. If there were 400 migrants in the country in the year 2000, What was the increase in the population of migrants during the period from 2009 to 2012?

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 #7200