Since there are a total of 156 eggs used, and 96 were already used, you subtract 156 - 96 = 60. Since there 12 eggs in each carton, you divide 60 by 12 to get 5.
A fraternity name formed by two letters would have 24 choices for the first letter, and 24 choices for the second, therefore 24*24=576 is the correct answer.
