Here let boys = b and girls = g

and total students = 100

i.e. b + g =100 --------- equ 1

10% of the students are member of school band = 10% of 100 = 10 students.

out of which 12% are boys and 8% are girls

i.e. 0.12b + 0.08g = 10 ----------equ 2

Now multiplying equation 1 by 0.12,

0.12b + 0.12g =12 ---------equ 3

equ 2 - equ 3

0.04g = 2

or g = 50

Hence b= 50 (from equation 1)

Therefore there are 50% fifth-grade students at the school are boys. option E
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Hello!!!
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