Since they buy 2 $6.50 tickets, they already spend $13 without buying any popcorn or drinks.
For the expression, you can write-
$5.50d + $6.00p + $13 // d representing however many drinks they buy and p representing the amount of popcorn they buy.
This expression will give you the total amount of money spent with varying amounts of drinks and popcorn bought.
This is what I get
You have to place the decimal numbers over the power of 10.since its 6 places to the right will be 10^6(1000000).
464646/1000000
Now cancel common factors by factoring out 2.
232323/500000=0.464646
The answer to the question
That would 32a - 8, Good Luck!