Question 973807
A=number of students in section A of class x
B=number of students in section B of class x
C=number of students in section C of class x
A=B
y=total marks for section A
z=total marks for section B
w=total marks for section C
A+B+C=50
2A+C=50
Two times the number of students in section A plus the number of students in section C equals 50 students.
(y+z)/2A=52.5
The total points for section A and B divided by the number of students in section A plus B.
(y+w)/(A+C)=60
(z+w)/(B+C)=70
(y+z+w)/(2A+C)=60

y+z=105A
(105A+w)/(2A+c)=60
2A+C=50
2A=50-C
(105A+w)/50=60
105A+w=3000
w=3000-105A
(y+3000-105A)/(50-A)=60
y+3000-105A=3000-60A
y=45A
45A+z=105A
z=60A
(60A+3000-105A)/(50-A)=70
-45A+3000=3500-70A
25A=500
A=20
40+C=50
C=10
There are ten students in sections C.