Answer:
average rate of change = 4
Explanation:
the average rate of change of f(x) in the closed interval [a, b ] is

here [ a, b ] = [ - 10, - 8 ] , then
f(b) = f(- 8) = 8 ← point on graph (- 8, 8 )
f(a) = f(- 10) = 0 ← point on the graph (- 10, 0 )
average rate of change =
=
=
= 4