Answer: Maximum area would be 225 sq. yard.
Explanation:
Since we have given that
Perimeter of rectangular pig sty = 60 yd
As we know the formula for "Perimeter ":

Since we need the maximum area she can enclose:
Square with same perimeter would enclose maximum area than the rectangle.
For this we assume l=b.
So, it becomes,

So, Maximum area would be

Hence, the maximum area would be 225 sq. yard.