For this case we propose a system of equations:
x: Let the variable representing the number of children in the concert
y: Let the variable representing the number of adults at the concert
According to the assistance we have:
According to the cost we have:
Substituting the first in the second equation we have:
Thus, the concert was 375 adults.
On the other hand we have:
Thus, the concert was 1125 children.
In total they were:
people
ANswer:
The concert was 1500 people