Question 599545
Area of rectangle = length*width
So (X + 3)*(X - 3) = 40
i.e. (X^2 - 9) = 40
X^2 = 40 + 9
X^2 = 49
X = sqrt(49)
X = 7

So length = 7 + 3 = 10 units & 
width = 7 - 3 = 4 units