The squiggly lines and the 2 straight lines through to sides of the pentagon mean that they are congruent (equal in length).
So, to find the perimeter of a regular polygon, you add all of its sides together.
So, the perimeter= 4x-2+x-2+x-2+x+2+x+2
To simplify it, add all of the x's together.
4x+x+x+x+x=8x
Perimeter=8x-2-2-2+2+2
-2-2=-4-2=-6+2=-4+2=-2
Perimeter=8x-2
Reach out to me if you have any questions. I'd be glad to help! :)