You are throwing a big party and want to have a large amount of beer so you are at the store to buy Bud Light. You have multiple choices of packages to choose from. Which size of Bud Light packs should you buy to minimize your cost, assuming any leftovers you would drink in the future.

- Eighteen packs at $14.40 each

- Twelve packs at $9.99 each

- Nine packs at $7.60 each

- Twenty-four packs at $19.50 each

- Six packs at $9.70 each with buy one get one free sale