Answer:
18
Step-by-step explanation:
We add up the side lengths,

by finding missing side lengths with subtraction and logic
and I'm pretty sure this is correct, but I like double-checking things.
This figure is made out of 2 rectangles,
2x5 and 3x2
The perimeter of each is 14 and 10

the two 3's are the over lapping sides
We also get 18.