186 children could attend.
The system of equations would be
A+C=320
8A+5C=2000
Solve the first equation for A by subtracting C from both sides:
A+C-C=320-C
A=320-C
Substitute this into the second equation:
8(320-C)+5C=2000
2560-8C+5C=2000
2560-3C=2000
Subtract 2560 from both sides:
2560-3C-2560=2000-2560
-3C=-560
Divide both sides by -3:
-3C/-3 = -560/-3
C = 186.7
Since we cannot have 0.7 of a child, there can be 186 children.
