Since the total is 64 ounces, but 18 ounces are already filled you only need to fill 46 ounces. If the dispenser is it 2 ounces per second just divide the amount needed by 2. Leave a comment if you need more help.
First, find out how many ounces left are needed to fill the water. Subtract the total, 64, by the already filled, 18. This should get you the answer of 46.
Since the dispenser fills 2 ounces per second, you need to divide the number 46 by 2 in order to find the amount of time in seconds it would take to fill the rest of the cup.
