196, because 20-4 equals to 16 and 16 times 12 equals 192, and 192 minus 6 is equal to 186.
By definition, the volume of a cone is given by:

Where,
r: radius of the circular base
h: height of the cone
Let's define a variable:
x: diameter of the base
We have then that the radio is:

The height is:

Substituting values:

Rewriting:
Answer:
An expression that represents the volume of the cone, in cubic units is: