Respuesta :
for every 3 boys, there are 7 girls.
X needs to be higher then 21 and lower then 35, so
21<X>35
X=n×(3+7)
X=n×10
n can only be 3 so that X can be 30
X = 3 × 10 = 30 students
if n is 4 for example
X = 4 × 10 = 40 which is higher than 34
X needs to be higher then 21 and lower then 35, so
21<X>35
X=n×(3+7)
X=n×10
n can only be 3 so that X can be 30
X = 3 × 10 = 30 students
if n is 4 for example
X = 4 × 10 = 40 which is higher than 34