GMAT Prep DS Problem

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Source: — Data Sufficiency |

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by Anurag@Gurome » Wed Mar 16, 2011 3:57 am
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by GMATGuruNY » Wed Mar 16, 2011 4:39 am
yellepeddi wrote:Need help solving GMAT Prep DS problem
Image
Plug in for the angles.

As we plug in, we have to satisfy the conditions in the problem and follow the rules of geometry.
Angles opposite equal sides of a triangle must be equal.
The sum of angles inside a triangle must be 180.
The sum of angles that form a straight line must be 180.

The goal is to see what happens to the value of x.
If x can be only 1 value, the statement is sufficient.
If x can be more than 1 value, the statement is insufficient.

Statement 1: QR = RS

Image

The drawing above shows that x can be more than 1 value.
Insufficient.

Statement 2: ST = TU

Image

The drawing above shows that x can be more than 1 value.
Insufficient.

Statements 1 and 2 combined:

Image

The drawings above show that x can be only 1 value.
The figure on the left and that on the right include different combinations of angles that satisfy the conditions in the problem and follow the rules of geometry.
In each case, x=45.
Sufficient.

The correct answer is C.
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