I see that 12 tickets is 4 times the 3 movie tickets.
So how much they pay for 12 tickets will also be 4 times the old amount of $15.75.
4*$15.75 = $63
You could also find how much one movie ticket is, then multiply the cost of one ticket by 12.
The cost of one ticket would be $15.75 / 3 = $5.25
Then 12 tickets would be 12($15.25) = $63