Question 480849
side of square = x
Are of square = x^2

Rectangle length = (x+12)
rectangle width = (x+8)
Area of rectangle = (x+12)(x+8)

(x+12)(x+8) =2x^2

x^2+20x+96=2x^2
x^2-20x-96=0
x^2-24x+4x-96=0
x(x-24)+4(x-24)=0
(x-24)(x+4)=0
ignore negative
x= 24 the side of square 
Perimeter of square = 24 *4 = 96cm

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