The population at MS 137 was 1850 students in the year 2009. In two years, by 2011, the population increased by 20percent. By 2013 the population decreased by 15percent. What was the population in 2013?

Step-by-step explanation:

1,850x20% = 370 (student population increased by 370 students in 2011)

1,850+370 = 2,220 (total number students in 2011)

2,220x15% = 333 (decreased by 333 students in 2013)

2,220-333 = 1,887 (total population of students in 2013)