Number of juice cups = 20
Capacity of a juice cup = 10 Ounce
So, Total Juice in All cups = 20 * 10 = 200 Ounces
We need to convert it into gallons, we know, 1 gallon = 128 Ounces
So, 200 Ounces = 200/128 = 1.56
So, As bottle cannot be in decimal or fraction, she have to purchase nearest greater number. She needs to purchase 2 juice bottles
Hope this helps!