A cup is 8 ounces, so ... two and a half.
Note that these are measuring cups. I have no idea what size your actual cups are; it could reasonably anywhere from about 6-16 ounces.
6.4 of them
There are 2.5 8 oz. cups in a 20 oz. glass. 20 divided by 8 equals 2.5.
That is about 20 cups.
40.
20 ounces of water is 2.5 cups
2.5 cups 1 cup = 8 ounces 1 ounce = 0.12 cup
20 cups
That is 20 cups
20 ounces is 2.5 cups. This is because each ounce is about 0.125 cups, so multiplied by 20 is a total of 2.5 cups.
20 cups of water is approximately 4.536 Kg
That is approximately 20 cups. imperial gallons to Canadian cups.
About 19 20-ounce bottles.