A= B+C
As given, A+B+C = 50000 seats
A+(B+C) = 50000
2A = 50000
A= 25000 seats
Now section A sells seats at $30 each
So,
Now, B+C = 25000
B = 25000-C
B sells at $24 and C sells at $18
So, 24B+18C = 538800
Now as section A incurs an amount of $750000 from booking, so B and C will incur 1288800-750000 = 538800 where $1288800 is the total booking amount.
24B+18C = 538800
6C = 61200
C = 10200
Now, B = 25000-C
B = 25000 - 10200 = 14800
Hence, section A has 25000 seats
Section B has 14800 seats
Section C has 10200 seats