What is the perimeter (please explain your answer)

Answer:
Answer: B. 38 mm
Step-by-step explanation:
The Perimeter of a Shape
The perimeter of a given shape is the sum of all exterior lengths surrounding the shape.
The figure shows a shape where all the external measures are given except the leftmost side.
This length is the sum of 3 mm + 10 mm = 13 mm.
Now calculate the perimeter:
P = 4 mm + 3 mm + 10 mm + 8 mm + 13 mm = 38 mm
Answer: B. 38 mm