Perimeter of a rectangle is 2 times the sum of the length and width
p=2(l+w) and we are told that p=54 and l=13+w so
54=2(13+w+w) divide both sides by 2
27=13+2w subtract 13 from both sides
14=2w divide both sides by 2
w=7, and since l=w+13
l=20
So the length of the lot is 20 meters.