Answer:
number of orchestra seats is 100
number of main seats is 240
number of balcony seats is 160
Explanation:
Let's assume that the number of orchestra seats to be x,the number of main seats to be y and that of balcony seats to be z.
From the first statement,
X + y + z = 500______ equation 1
From the second statement,
60x + 45y + 30z= 21600_____ equation 2
From the third statement,
30x + 45y + 30z = 18600______ equation 3
From equation 1,we make x the subject of the formula
X = 500 - y - z
Apply the above in equation 2 and 3
60(500 - y - z) + 45y + 30z = 21600
30000 - 60y - 60z + 45y + 30z = 21600
15y +30z = 8400____ equation 4
And
30x + 45y + 30z = 18600
30(500 - y -z) + 45y + 30z = 18600
15000 - 30y - 30z + 45y + 30z = 18600
15y = 3600
Y = 240
Replace y = 240 in equation 4
15y +30z = 8400
15(240) + 30z = 8400
3600 + 30z = 8400
30z = 4800
Z = 160
Now remember that x + y + z = 500
X + 240 + 160 = 500
X = 100
X which is number of orchestra seats is 100
Y which is number of main seats is 240
And x which is number of balcony seats is 160