Length (L) = 42
Width (W) = 18
and the equation which helps to find the width of the garden is
            L = 6 + 2W
Now, we have to find the length and width of the garden area.
It is given that,
we know that the Length is 6 feet more than twice the width, this in other words, it means that:
                     L = 6 + 2W    -------------------------(1)
So, let's denote W as X
The perimeter of the garden is 120 and the expression to calculate is:
                     P = 2W + 2L    ------------------------(2)
Replacing all the values in the above expression we have the following:
                   120 = 2x + 2(6 + 2x) ---------------------(3)
Solving for x from the above equation (3), we have:
⇒120 = 2x + 12 + 4x
⇒120 - 12 = 6x
⇒108 = 6x
⇒x = 108/6
⇒ x = 18
So the Width is 18, therefore the Length from equation (1):
        L = 6 + 2(18)
       ⇒L = 6 + 36
       ⇒L = 42
Learn more about  Perimeter:
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