Answer:
84
Step-by-step explanation:
Let A be the number of students in grade 7
Let B be the number of students in grade 8
we have [tex]\frac{A}{B} =\frac{3}{4}=\frac{36}{B}[/tex]
===> B (number of students in grade 8) = 4x36/3=48
so there are 48+36= 84 students in school band