Answer:
28 units.
Explanation:
The perimeter of the left triangle is (6x+3) + (4x) + (2x+1).
This simplifies to 12x + 4.
The perimeter of the right triangle is (5x) + (5x) + (3x+2).
This simplifies to 13x + 2.
You are told the perimeters are the same, so 12x + 4 = 13x + 2.
If you take 12x away from both sides, you get 4 = x + 2.
If you take 2 away from both sides, you get x = 2.
Now, you need to work out the perimeter, so substitute x into either 12x + 4 or 13x + 2 (it doesn't matter which, as you are told they are the same).
If you choose 12x + 4, then 12(2) + 4 = 24 + 4 = 28 units for the perimeter.
If you choose 13x + 2, then 13(2) + 2 = 26 + 2 = 28 units for the perimeter.