I think the answer should be 54 pi centimeters but I can't see all the options, area of a circle is pi r^2 so if the diameter is 18, diameter = 2r so the radius is 9. pi 9^2 is 81 pi, then the same for the 3 unshaded ones and just subtract the area of the 3 white circles (27 pi) out of 81 pi.
