Answer:
625 sq. m.
Step-by-step explanation:
The graden's area is given as :
For maximization of area,we need to put first order derivative of given equation equals to 0 i.e. a'(w) should be equal to zero.

On Simplifying :

w = 25 meters
Since we are given that Shenelle has 100 meters of fencing to build a rectangular garden
This means perimeter is equal to 100.
Formula of perimeter of rectangle : 
Where l is length
w is width
Plugging w as 25

Dividing 2 in both sides


So, for the maximum area the length should be 25 m and width should 25 m
So, So, maximum area 
Hence the maximum possible area is 625 sq. m.