Answer :
To start: A = 1/2bh
Now by increasing both the width and height by 9, you get: A = 1/2(9b)(9h) = 1/2(81)bh
You can see that the increase in area is 81 times the original.
Now by increasing both the width and height by 9, you get: A = 1/2(9b)(9h) = 1/2(81)bh
You can see that the increase in area is 81 times the original.