For every boy taking classes at the music school, there are 3 girls who are taking classes at the school. If there 128 students taking classes, write and solve a proportion to predict the number of girls taking classes at the school.

Answer 1

boy : girls = 1 : 3 or x : 3x
x + 3x = 128
4x = 128
x = 32

so 32 girls and 3x or 96 girls take music

or

3/4 = n/128 , where n is the number of girls
4n = 384
n= 384/4 = 96