The picture is above I’ll mark as brainliest.

Answer:
Width = 3 m
Step-by-step explanation:
Formula for perimeter:
P = l + w + l + w
Plug in what we know:
14 = 4 + w + 4 + w
Isolate variable w (width):
14 = 8 + 2w
6 = 2w
3 = w
Check your work:
14 = 4 + 3 + 4 + 3
14 = 7 + 7
14 = 14
Correct!
(Don't forget to add units in your answer!)