A furniture store makes two types of chairs: rockers and swivels. To make a rocker, the store must run machine A for 2 hours and machine B for 3 hours. In order to make a swivel, the store must run machine A for 4 hours and machine B for 1 hour. Machine A can be run no longer than 20 hours in a day. Machine B is limited to 15 hours per day. The store makes a profit of $12 from each rocker chair and $10 from each swivel chair. How many ROCKER chairs should be made each day to maximize profits?