Explanation:
Let's call the number of orchestra seats "O", the number of main seats "M", and the number of balcony seats "B". We can write the following two equations to represent the given information:
O * $140 + M * $135 + B * $90 = $59,100
0.5 * O * $140 + M * $135 + B * $90 = $50,700
Subtracting the second equation from the first, we get:
0.5 * O * $140 = $59,100 - $50,700 = $8,400
Dividing both sides of the equation by 0.5 * $140, we get:
O = $8,400 / ($140 * 0.5) = 30 seats
Substituting this value back into the second equation:
0.5 * 30 * $140 + M * $135 + B * $90 = $50,700
Expanding and simplifying:
$2100 + M * $135 + B * $90 = $50,700
Subtracting $2100 from both sides:
M * $135 + B * $90 = $50,700 - $2100 = $48,600
Dividing both sides of the equation by $135:
M + B = $48,600 / $135 = 360 seats
Finally, since the total number of seats is 490:
M + B + O = 490
Substituting the values of O and M from above:
360 + 30 = 390 + 30 = 490
So there are 360 main seats and 30 balcony seats.