Suppose you need to put a fence around a rectangular garden that has a perimeter of 64ft. the width is 12ft less than the length. find the length and width of the garden

Perimeter of the rectangular garden as given in the question = 64 feet
Let us assume the length of the rectangular garden = x feet
Then
The width of the rectangular garden = x - 12 feet
So
Perimeter of the rectangular garden = 2 ( length + width)
64 = 2 (x + x - 12)
64/2 = 2x - 12
32 = 2x - 12
32 + 12 = 2x
2x = 44
x = 44/2
   = 22
So
The length of the rectangular garden = 22 feet
And
The width of the rectangular garden = x - 12 feet
                                                           = 22 - 12 feet
                                                           = 10 feet