A carpenter makes bookcases in two sizes: large and small. It takes 6 hours to make a large bookcase and 2 hours to make a small one. The profit on a large bookcase is $50 and the profit on a small bookcase is $20. The carpenter can only spend 24 hours per week making bookcases, and must make at least two of each size each week. How many of each size must be made per week in order to maximize profit?