Answer:
0.3 is the answer I think it is, but see below.
Explanation:
So the question is what is x to accomplish this?
2x + 1.5x + x = 0.9
The exact question wants to know about the middle shelf. The question as written is not a certainty. Let's get x, then we'll see about that middle shelf.
Add the left side
4.5 x = 0.9
Divide by 4.5
x = 0.9/4.5
x = 0.2 meters.
Now to what is being asked. I think you are intended to answer 1.5x which is 1.5*0.2 = 0.3 meters.
But it could also mean how far from the ground is the middle shelf.
In that case 2*0.2 = 0.4 meters from the ground is where the middle shelf is located. It's hard to tell.