The semi-major axis will be (30 - (9-(-9)))/2 + 9 = 15 units long. The semi-minor axis will be √((30/2)^2 - 9^2) = 12 units long. The center is located at (0, 0) An equation is

**(x/15)^2 + (y/12)^2 = 1**__Check__We expect points (-15, 0) and (0, 12) to be on the ellipse. (-15/15)^2 + (0/12)^2 = 1 (yes) (0/15)^2 + (12/12)^2 = 1 (yes)