For side length s, the area of a square is given by
... A = s²
Then the side length can be found to be
... s = √A = √(506.25 ft²) = 22.5 ft
The perimeter is the sum of the lengths of the four equal sides.
... P = 4s = 4·(22.5 ft) = 90 ft
Stevan will need 90 ft of fence to complete the job.
