Answer:
The length of one side of the square is 3.
Explanation:
The perimeter of any given shape is all of the sides added together. So, the perimeter of the triangle is 5x + 4x + 3x. Added together, 12x.
The perimeter of the square is (x + 2)*4. Distributed, it's 4x + 8. Since we know they're equal, set it up like this:
12x = 4x + 8
You then find that x = 1. Plug that into one side of the square, x + 2, to get 3.