<PRE><B>Question 754103</B>
perimeter = 2*length + 2*width
Area = length * width
Length = y  Width = x
Area = y * x
84 = y*x
Length (y) = 84/x
Substitute y = 84/x into 
Perimeter = 2*y + 2*x
  40 = 2*84/x + 2x
  40 = 168/x + 2x
multiply through by x
  40x = 168 + 2x^2
Rearrange
  2x^2 - 40x + 168 = 0
Divide through by 2
   x^2 - 20x + 84 = 0

  (x - 6)(x - 14)
Therefore length = 6cm and width = 14 cm
OR        length = 14cm and width = 6cm

Hope this helps
:-)
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