Find the ticket unit cost: divide the total paid, $324, by the number of tickets, x. Then the form of the unit cost is
$324
--------- .
x
This question is highly unusual in that you write "x" as the number of tickets sold, instead of a specific number of tickets. Supposing that you'd sold 100 tickets for $324, then the unit cost would be, much more typically, a numeric ratio:
$324
----------------- = $3.24/ticket
100 tickets
The constant of proportionality (r) appears to be 3.
y = 3x . . . . . . . x = number of tickets sold; y = dollars collected
x = 15°
The angle of a straight line is 180°.
37 + 9x + 8 = 180
9x + 45 = 180
9x = 135
x = 15°