For a function f(x), the difference quotient is x + one-half h + 15. Which statement explains how to determine the average rate of change of f(x) from x = 5 to x = 8? Substitute 5 for x and 3 for h in the expression x + one-half h + 15. Substitute 5 for x and 8 for h in the expression x + one-half h + 15. Substitute 8 for x and 5 for h in the expression x + one-half h + 15. Substitute 8 for x and 3 for h in the expression x + one-half h + 15.