Suppose that there are two types of tickets to a show: advance and same-day. The combined cost of one advance ticket and one same-day ticket is $55
. For one performance,
40
advance tickets and
25
same-day tickets were sold. The total amount paid for the tickets was
$1900
. What was the price of each kind of ticket?

This is the entire problem:
Suppose that there are two types of tickets to a show: advance and same-day. The combined cost of one advance ticket and one same-day ticket is $ 40. For one performance, 25 advance tickets and 30 same-day tickets were sold. The total amount paid for the tickets was $1075 . What was the price of each kind of ticket?

Set up a set of 2 equations in 2 variables -
Let x = advance ticket cost and y = same-day tickets cost
Then
x+y=40 and
25x+30y=1075 >>>>> 5x+6y=215
x=40-y, so
5(40-y)+6y=215
200-5y+6y=215
y=15 >>>> x=25

5(25) + 6(15) = 125+90 = 215

The second step on the test was the move he was supposed to