If u get all 3 right ill put u as brainiest!

13

Step-by-step explanation: Alright with the median you take all the numbers "11, 20, 17, 8, 8, 9, 20, 13, 21" and put them in numerical order. "8, 8, 9, 11, 13, 17, 20, 20, 21" Then the middle one is the median, since there are 9 numbers you take the fifth one. In this case it is 13. (Only knew the first one since I have no idea what they mean by quartiles)

hello from mrbilldoesmath!

answer:

x - 3

discussion:

x^2 - 9 = (x-3) (x+3)   so

(x^2-9)/ (x + 3) = x-3

you,

mrb