We know that pupils are students
Students = S
boys = B
Teachers = T
So....
S = 8T
Boys = 3G
T = B - 70
Since there is 8x students than teachers, I did Boys = 6x and girls = 2x
I'm going to use this next: S = 8T
8x = 8(B -70)
8x = 8(6x - 70)
8x = 4x - 560
x = 14
We know there is 8x students, so there are 112 students and we know that there is 1/8 of teachers, so there are 14 teachers.
Answer = 126.