Answer:
31 adults, 62 children, and 86 students.
Step-by-step explanation:
The seating capacity of the movie theatre = 179
Children's(c) Ticket = $5.00
Student's(s) Tickets = $7.00
Adult's(a) Tickets = $12.00
There are half as many adults as there are children.
The total ticket sales was $1284
We then solve the three resulting equations simultaneously.
c+s+a=179
c=2a
5c+7s+12a=1284
We substitute c=2a into the first and third equation

Substitute s=179-3a into 22a+7s=1284

Recall:
c=2a
c=2*31
c=62
Finally:
c+s+a=179
62+s+31=179
s=179-62-31
s=86.
Therefore:
31 adults, 62 children, and 86 students attended the movie theatre.