The answer is 25 days. To get this answer the first thing to do is change 2 1/2 to 2.5. We are going to divide 64 cups by 2.5 to get the number of days Carl can feed his dog his full 2 1/2 cups. The answer is actually 25.6 but the question is what is the maximum number of days he can feed his dog exactly 2 1/2 cups.
~Hope this helps!