Question 313815
Hello, 
We know that the measure of the square is 9 cm by 9 cm. Let's represent each side as "x". Let's represent the amount added and subtracted as "y". The equation that can be set up is:
x^2-9=(x+y)(x-y) This can be rewritten as:
x^2-9=x^2-y^2 The x^2 cancels out leaving us:
-9=-y^2 Divide by -1 and sq rt to get:
y=3
Therefore we can solve this rectangle size as 12 cm by 6 cm. The area comes out to be 72 cm^2. It works out. 
Makes sense?
RJ 
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