Answer:
9x = perimeter
Explanation:
The dash through all of those lines shows us that they are all the same size.
Knowing one line is x, every line with the same amount of dash marks through it is also x.
add the amount of lines with one dash mark together.
There are 9 lines with a dash through them, so all 9 lines are an identical size.
multiply that by x, since they are all x units long.
9x
That is your perimeter, so 9x = perimeter.