Answer:
How many are there of each kind of seat?
orchestra 100, main 230, and balcony 170
Explanation:
x = Orchestra seats
y = Main seats
z = Balcony seats
x + y + z = 500
:
If all the seats are sold, the gross revenue to the theatre is $13,150."
40x + 25y + 20z = 13150
:
"but if only half the orchestra seats are sold, the gross revenue is $11,150."
(40÷2)x) + 25y + 20z = 11150
20x + 25y + 20z = 11150
use elimination on these two equations
40x + 25y + 20z = 13150
20x + 25y + 20z = 11150
20x = 2000
x = 2000÷20
x = 100 orchestra seats
100 + y + z = 500
y + z = 500 - 100
y + z = 400
25y + 20z = 9150
20y + 20z = 8000
5y = 1150
y = 1150÷5
y = 230 Main seats
100 + 230 + z = 500
z = 500 - 330
z = 170 Balcony seats