Final answer:
There were 69 children, 83.5 students, and 34.5 adults in attendance at the movie theater.
Step-by-step explanation:
To solve this problem, we can set up a system of equations.
Let's denote the number of children as 'c', the number of students as 's', and the number of adults as 'a'.
From the given information, we have the following equations:
c + s + a = 187 (equation 1)
5c + 7s + 12a = 1356 (equation 2)
We also know that there are half as many adults as children, so we have the equation:
a = (1/2)c (equation 3)
Substituting equation 3 into equations 1 and 2, we can solve for the variables.
Substituting (1/2)c for a in equation 1:
c + s + (1/2)c = 187
(3/2)c + s = 187 (equation 4)
Substituting (1/2)c for a in equation 2:
5c + 7s + 12((1/2)c) = 1356
5c + 7s + 6c = 1356
11c + 7s = 1356 (equation 5)
Now we can solve equations 4 and 5 simultaneously:
Multiplying equation 4 by 11:
(33/2)c + 11s = 2057/2
11c + 7s = 1356
Subtracting the second equation from the first:
(33/2)c - 11c = 2057/2 - 1356
(-1/2)c = -69/2
c = 69
Substituting c = 69 into equation 4:
(3/2)(69) + s = 187
103.5 + s = 187
s = 83.5
Finally, substituting c = 69 and s = 83.5 into equation 3:
a = (1/2)(69)
a = 34.5
Therefore, there were 69 children, 83.5 students (which is not a whole number, so it could be rounded to 84 students), and 34.5 adults (which could be rounded to 35 adults) in attendance at the movie theater.