Initially 40% percent of the students at the school dance are freshman. Then 15 more freshman arrive,after which 52% are freshman.How many students are now at the dance after the freshman arrive?

Let the number of students = S

52% - 40% = 12 % percentage rise as a reult of arrival of 15 freshmen.

12%S = 15

0.12S = 15

S=15 / 0.12 =125 - number of students at the dance after the arrival of 15 freshmen.