What is the value of x, given that the two pyramids are similar?

C

Step-by-step explanation:

Two pyramids are similar. It means that their side lengths are proportional.

So, let's see the proportionality constant from SMALL PYRAMID to LARGE PYRAMID.

The corresponding length of 8 in small pyramid is 24 in large pyramid. We ask ourself:  "8 times WHAT gives us 24?"

This is the proportionality constant (aka "k").

So, 8 times "3" is 24. So the proportionality constant is "3".

k = 3

Now, the height of small pyramid is 6 and height of large pyramid is "x". These sides will be same way proportional. So, we can say:

6 times the proportionality constant (3) would give us x

So,

6 * 3 = x

x = 18

Correct answer is C