1 gallon = 16 cups
The picture that was attached to this question talked about 1 1/2 gallons. So assuming that you need to solve for how many cups are there is 1 1/2 gallons you need to do:
We know that 1 gallon = 16 cups, so 1 1/2 (or 3/2) gallons would equal to:

, which would equal to
24 cups.