Let x = number of tickets sold.
$15x = $19,950
x = $19,950 ÷ $15
x = 1,330
So, 1330 tickets * $20 each = $26,600.
Let y = how much more the school makes at $20 per ticket.
y = $26, 600 - $19, 950
y = $6,650
The school will make $6,650 more at $20 per ticket.