"x" always goes on the left side and "y" always goes on the right side of the parentheses. If you only have an "x" then you will just put a zero in for "y" and vice versa. I hope this helps.
Step-by-step explanation: So if shawn downloads 5 movies at $2 a piece, that makes 10 dollars worth of movies, but it he gets a 25% discount that means he spends $2.50 less than $10 which is $7.50.