GmatPrep - DS

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Source: — Data Sufficiency |

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by pepeprepa » Fri Aug 22, 2008 1:38 am
I don't like this kind of question, they can put some traps.

X: original jacket
Y: original t-shirt

We look for 0.85*X - 0.9*Y

1)
They tell us that 83=X - Y
We don't have 2 equations so there is a problem. You can tell you that the difference will depend on the values of X and Y, even if the original difference is 83, the new difference between numbers which are multiplied by 85% and 90% will not be the same.
For example,
100-17= 83 --> 85 - 15,3=69,7
200-17=83 --> 170 - 105,3=64,7

2)
X=140
X-Y=140-Y
0.85*X - 0.9*Y cannot be solved we do not know Y

1)and2)
We have the original difference and the value of X
140-Y=83
You find X and it is ok