a) Here is a diagram of the rectangular garden with 4 sides enclosed by 40 meters of fencing:
```
+----x----+
| |
x x
| |
+----x----+
```
b) Let x represent the width of the garden. Since there are 4 sides, two sides will have length x and the other two sides will have length L. The total length of the fencing is given as 40 meters. So, we can write:
2x + 2L = 40
c) To find the expression for the length of the garden in terms of x, we can rearrange the equation from part b) as follows:
2L = 40 - 2x
L = 20 - x
d) Here is a sketch of the graph of the garden area:
```
^
| A(x)
|
+-----------------
0 x
```
e) To find the maximum area of the garden, we can use the area function A(x) expressed as:
A(x) = x(20 - x)
To find the maximum, we can take the derivative of A(x) with respect to x and set it equal to zero:
A'(x) = 20 - 2x = 0
Solving for x, we find:
20 - 2x = 0
2x = 20
x = 10
So, the maximum area of the garden can be found when the width is 10 meters.