For any sort of pyramid or cone, the volume is 1/3 of the volume of a prism with the same base and height. Since the volume of a prism/cylinder is

, the volume of a pyramid/cone is

.
In this case, our base is a circle, which has a radius of 4 cm.
The area of a circle is

where r is the radius.

We now know that our base is 16π cm.
We also know that our height is 9 cm.
Let's plug these into our volume formula.

Use 3.14 to approximate pi as the question states. 16 × 3.14 = 50.24.

We could punch all of that into our calculator to get the same answer, but since 1/3 of 9 is clearly 3, let's just go with that.

Answer:
The answer is x=12.
Step-by-step explanation:
First, to solve this equation you need to isolate the x variable. To isolate the variable, you must, subtract the other term from both sides. Subtracting 18 from both sides, you are left with 3x = 36. Since 3 times x = 36, dividing both sides by 3 gets you, x=12.
D is the answer to your question
Here you go. Just remember PEMDAS.
P-parentheses
E- exponents
M-multiplication
D-division
A-addition
S-subtraction
That is the order you will do it in.