So the equation would be 52/x (x being the number of total number of 7th graders) and 26/100 (100 being 26% out of 100%).
You do cross multiplying which would be 52/x = 26/100 ------ 5200 = 26x
You divided 26 by both sides.
5200/26=200
There are 200 7th graders total.