Answer:
$36 (see below)
Step-by-step explanation:
First, you have to find how much they paid for one ticket.
If they paid $12 for 3, then they paid $4 for 1.
You could've also use a ratio:
$12 $x
-------- = --------
3 1
Cross multiply:
$12 (1) = $3x
$12 = $3x
$4 = x
So $4 for 1 ticket.
To find the cost of 9 tickets, just multiply the price by the number of tickets, which is:
$4 (9) = $36
