Answer:
9 students
Step-by-step explanation:
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
$21.60 - $18.00 = $3.60
$3.60 : $18.00 = 0.2
0.2 · 100% = 20%
Answer:
first is -3, second number is 0
Step-by-step explanation:
you have two equations x+3=y and 4*x+12=5*y
Use the first one and write y in terms of x in the second equation:
4*x+12=5*(x+3)
4*x+12=5*x+15
12=5*x-4*x+15
12=x+15
x=-3