Final answer:
The form of the equation used to model the price of a gallon of milk cannot be determined without the table data.
Step-by-step explanation:
The form of an equation used to model the price of a gallon of milk can be determined by analyzing the given data in the table. Based on the information provided, we can determine whether the equation is linear, quadratic, exponential, or some other form. However, as the table data is not provided in the question, it is not possible to determine the specific form of the equation for modeling the price of a gallon of milk.