Step-by-step explanation:
a fence represents the circumference, the perimeter of the lot or yard.
remember, a rectangle has 2 parallel sides called the length, and 2 parallel sides called the width (altogether 4 sides).
therefore
perimeter = 2×length + 2×width
or with short variables
p = 2×l + 2×w
so, now we have 50 ft of fence available for the perimeter. and the length l = 13 ft.
since we have 2 lengths in the perimeter, these 13 ft are twice (2×13 = 26 ft) in the perimeter.
now, how much fence do we have left for the width ?
well, 50 - 26 = 24 ft
and again, this is the size of 2 sides (2×width) :
p = 2×l + 2×w
50 = 2×13 + 2×w = 26 + 2×w
2×w = 24
w = 12 ft
so, the width of the yard must not be bigger than 12 ft.
