Your variable is always the number of drinks that you are going to drink, and the independent clause is the cost of the drink, which is $2.5.
Drinks Cost
1 2.5
2 5
3 7.5
4 10
5 12.5
SO now you know that the cos of 3 drinks is 7.5 and that can be escalated to any number that you want just by puttin the number of drinks that are going to be bought and multiply it by the cost.
