SOLUTION: if the length of a rectangle is increased by 10% and the area is unchanged , then by what percentage must the width be decreased ?

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Question 173517: if the length of a rectangle is increased by 10% and the area is unchanged , then by what percentage must the width be decreased ?
Found 2 solutions by Mathtut, ankor@dixie-net.com:
Answer by Mathtut(3670) About Me  (Show Source):
You can put this solution on YOUR website!
L+W=A
:
if L is increased by 10%
:
then
:
(11/10)L(W)=A
:
W=%2810%2F11%29A

Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
if the length of a rectangle is increased by 10% and the area is unchanged , then by what percentage must the width be decreased ?
:
Let L & W be the original length and width
:
1.1L = new length
xW = new width
:
New area = old area
1.1L * xW = L * W
Divide both sides by L
1.1 * xW = W
Divide both sides by 1.1
xW = W%2F1.1
Divide both sides by W
x = 1%2F1.1
x ~ .91, original width reduced by 9%