With the wording you presented in your problem statement, I am assuming that you need both 2 empty bottles and 5 bottle caps to get 1 free drink. If you intended to state 2 empty bottles OR 5 bottle caps, then Nick's answer would be correct. Otherwise, assuming your statement as written is correct, then your initial $10 allows you to buy 5 drinks. From these drinks, you can obtain 5 bottle caps and 5 empty bottles, which allows you to obtain 1 drink. This extra drink will now give you 3 empty bottles and 1 bottle cap.
The wording of the problem should be double checked so you can properly evaluate the answers presented here.