Hello, I'll try to make this as easy to understand as possible, anyways, let's begin:
In this problem, we need to only count the cubes, and multiply by 2.
As we can see, we have 18 blue cubes, we can see that the red cubes below are the same as the blue ones, so we just multiply:
18*2 = 36
So that means...
The answer is 36.
Hope this helped! c: