Answer:
159 students.
Since all you need to do is multiply 120×1.3/4=39, then you add 120, as we are told that there are 120 boys. Basically, there are 39 girls and 120 boys, since by multiplying 20×1.3/4 equals 39, so 39 girls, and 120 boys. Now add them all together, 120+39=159.
Hope I helped!
