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:
The answer is 5.1 when you enter it into a calculator :)
Re-written, I believe the equation is:
(W+23)+5=W+(23+5)
With this, the parenthesis have nothing multiplying into it, so we can drop the parenthesis to get:
W+23+5=W+23+5
Which is the same thing.
So I'd assume it is the Associative property, because you are combining the like terms of 23 and 5.
Hope this helps!