Okay, so what you want to do (by the way, do you know how many answers I've started off that way??!! TONS!!!) is divide 216.24, which is the area, by the height, which is 15.9. See, if you had the base and the height, you would multiply them together to get the area. But now you have the area and height, so to get the base, you divide. You end up getting 13. 6. You can check it by multiplying 13.6 and 15.9. Have a nice day!