Answer:
The average rate of change is -2
Step-by-step explanation:
we know that
To find out the average rate of change, we divide the change in the output value by the change in the input value.
In a linear function the average rate of change is a constant and is equal to the slope of the function
The linear function in slope intercept form is equal to

where
m is the slope or unit rate of the linear function
b is the y-intercept or initial value of the linear function
In this problem we have

so

therefore
The average rate of change is -2