Answer:
76 m
Sorry if this answer is not correct, if it is or is not, please tell me in the comments!
Explanation:
First of all, we know all of the sides already except for two, so we need to find them. (The side on the very left and top).
The side on the very top is 18 since the top and bottom are the same lengths. This also implies to the side on the very left. The sides (4+4+4) is equivalent to the side we are trying to find. We now know it is 12.
Second, to find the perimeter of almost every shape, we add all of the sides together.
18+4+8+4+8+4+18+12
This gives the answer of 76 m. (don't forget the label!)