Answer:
2.5 cups or 20 fl oz of water
Explanation:
Ounces (oz) is used for weight measurements
Fluid ounces (fl oz) is used for capacity measurement for liquids.
1 fluid ounce (fl oz) ≅ 1 ounce (weight) for water only
so 20 ounce of water = 20 fl oz
1 fluid ounce = 0.25 cups
20 fluid ounces= 20*0.25= 2.5 cups
So,
The bottle that Robert bought can hold
2.5 cups of water
20 fl oz of water