Answer:
Number of advance tickets sold = 30
Number of same-day tickets sold = 20
Explanation:
Let,
x be the number of advance tickets sold
y be the number of same-day tickets sold
According to given statement;
x + y = 50 Eqn 1
25x + 20y = 1150 Eqn 2
Multiplying Eqn 1 by 25
25(x+y=50)
25x + 25y = 1250 Eqn 3
Subtracting Eqn 2 from Eqn 3
(25x+25y)-(25x+20y) = 1250 - 1150
25x + 25y - 25x - 20y = 100
5y = 100
Dividing both sides by 5

Putting y = 20 in Eqn 1
x + 20 = 50
x = 50 - 20
x = 30
Hence,
Number of advance tickets sold = 30
Number of same-day tickets sold = 20