Answer:
1/2 gallon
Explanation:
Each full gallon can be represented as 4/4 of a gallon. Since Katie bought 2 one-gallon bottles, the total amount of juice is 8/4 gallons. The number line below represents the fraction of juice that her guests drank.
![\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ |\\\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\\\ (1)/(4)\ \ (2)/(4)\ \ (3)/(4)\ \ (4)/(4)\ \ (5)/(4)\ \ (6)/(4)\ \ (7)/(4)\ \ (8)/(4)](https://img.qammunity.org/2021/formulas/mathematics/high-school/wfuixlhm4fqnhaz82uclldbivf9fi7vwpg.png)
The fraction of a gallon of juice left over is:
![f=(8)/(4)-(6)/(4) =(2)/(4)\\f=(1)/(2)](https://img.qammunity.org/2021/formulas/mathematics/high-school/y72dhs0lqo026htgpp33q2dhd4k9766rfw.png)
Therefore, there is 1/2 of gallon of juice left over.