The answer is 0
------------------------------------
Work Shown:
Notice how when x = 0, the value of y is y = -4. So (0,-4) is on the curve.
Similarly, (7,-4) is also on the curve.
Because the y coordinates are both the same, the two points form a horizontal line with slope 0. We can see this through the slope formula
m = (y2-y1)/(x2-x1)
m = (-4-(-4))/(7-0)
m = (-4+4)/(7-0)
m = (0)/(7)
m = 0
Therefore, the average rate of change on this interval is 0