Given the function h(x)=-x^2+8x+24, determine the average rate of change of the function over the interval 0 is less than or equal to x is less than or equal to 9

Trang is planting shrubs beside the highway for his job. he needs to plant 500 shrubs this week. he planted 84 shrubs on monday, 92 shrubs on tuesday, 87 shrubs on wednesday, and 104 shrubs on thursday. how many shrubs does trang need to plant on friday to finish the job?