A warehouse store sells 3.5-ounce cans of tuna in packages of 8. A package of 8 cans costs $6.72. The store also sells 6.5-ounce cans of the same tuna in packages of 4. A package of 4 cans costs $7.28. The store sells 5.5-ounce cans in packages of 6 cans for $7.26. Which package is the best buy?