Width of the playground is 33 foot.
<u>Explanation:</u>
A fence around the playground represents the perimeter.
If the playground is rectangular in shape, then the perimeter of the rectangle is known.
Perimeter of the rectangle = 144 foot
Let, width = b foot
Given:
length (l) = b+6 foot
We know,
Perimeter of the rectangle = 2 (l + b)
Putting the values of l and b in above equation we get,

length (l) = 33 + 6 foot
l = 39 foot
Hence, width of the playground is 33 foot.