Answer:
The average rate of change from year 0 to year 2 is

The average rate of change from year 3 to year 6 is

Explanation:
The average rate of change describes the average rate at which gas price in dollars per gallon is changing with respect to time (years)
The given polynomial function is

Calculate the average rate of change from year 0 to year 2.
For year x = 0

For year x = 2

The average rate of change from year 0 to year 2 is

The negative sign indicates that the gas price has decreased from year 0 to year 2.
The average rate of change from year 3 to year 6 is
For year x = 3

For year x = 6

The average rate of change from year 3 to year 6 is

The negative sign indicates that the gas price has decreased from year 0 to year 2.