Aconical tank has an inside diameter of 20 ft and a height of 12 ft. the tank is filled with liquid to a height of 9 ft. how much liquid is in the tank? (round your answer to the nearest whole number.)

Check the picture below

so.. if you notice, the diameter is 20, the radius is half that, the radius and height are at a ratio of 5:6, if the larger cone is filled up to 9ft, that means, the conical gap above, is 3ft in height

so, simply getting the volume of the larger cone filled up, with a height of 12, and then subtracting that conical gap, you'd end up with what's leftover, whatever the volume is at 9ft

The answer is d 18ft