First I would turn the 1 1/3 cups into an improper fraction. That makes the math a little easier. 1 1/3 = 4/3. You know that 4/3 cups makes two dozen cookies. So, if you take half of 4/3 which is 2/3 that is how many cups it takes to make one dozen. Then to find how many cups it would take to make 5 dozen just multiply 2/3 by 5 to get 10/3 or 3 1/3!