At the north campus of a performing arts school, 20% of the sutdents are music majors. At the south campus, 50% of the sutdents are music major. The campuses are emerged into the east campus. If 21% of the 300 students at the east campus are music majors, how many students did each of the north and south campuses have before the merger.

Solution:

North: x

South: 300-x

So the equation is

20%*x + 50%*(300-x) = 21%*300

x = 290

So

North: 290

South: 10