Raj bought a 20-ounce can of powdered lemonade mix. He already has used some of the mix. Each quart of lemonade requires 2.5 ounces of the mix. Let q represent the number of quarts of lemonade Raj has made so far.
Which expression represents the amount of powdered lemonade mix left in the can?
A. 20q – 2.5
B. 20(2.5) – q
C. 20 – 2.5q
D. 2.5q – 20