Answer:
7cm
Explanation:
One side of a square is increased by 8 cm, let us say the length got increased by 8 cm. So we have length of x + 8 cm
An adjacent side, the width, decreased by 2 cm. So we have width of x - 2cm
Perimeter of rectangle = 2(length + width)
40 = 2( (x + 8) + ( x - 2) )
40 = 2( 2x + 6)
40 = 4x + 12
28 = 4x
x = 7 cm
That is 7 cm of the length of the side of the square