**Solution:**

Let x be the width and y be the length of the rectangular garden.

So, as per the given question,

y = x + 4 ….(i)

and half the perimeter is given as 36 m.

That means, x + y = 36 ….(ii)

From equation (i),

y = x + 4

x | 0 | 8 | 12 |

y | 4 | 12 | 16 |

From equation (ii),

y = 36 – x

The graphical representation of both equations is as follows;

From the above graph, we can see that the lines intersect each other at a point(16, 20).

Hence, the width of the garden is 16 m and the length is 20 m.