AbeNeedsAnswers wrote: ↑Fri Jun 05, 2020 6:13 pm
OG2021DS296.png
What is the value of z in the figure above?
1. x = 50
2. y = 35
C
Target question: What is the value of z in the figure above?
This is a great candidate for
rephrasing the target question.
Since angles on a line add to 180°, we can conclude that the missing angle in the triangle =
(180 - z)°
Now let's focus on the triangle.
Since angles in a triangle add to
180°, we can write: x° + y° +
(180 - z)° =
180°
Simplify: x + y + 180 - z = 180
Subtract 180 from both sides of the equation to get: x + y - z = 0
Add z to both sides of the equation to get:
x + y = z (this relationship is known as the exterior angle theorem: https://www.onlinemathlearning.com/exte ... eorem.html)
Since
z = x + y, we can rephrase the target question as follows
REPHRASED target question: What is the value of x + y?
Aside: Here’s a video with tips on rephrasing the target question: https://www.gmatprepnow.com/module/gmat- ... cy?id=1100
Statement 1: x = 50
Since we don't have any information about the value of y, there is no way to answer the
REPHRASED target question with certainty
Statement 1 is NOT SUFFICIENT
Statement 2: y = 35
Since we don't have any information about the value of x, there is no way to answer the
REPHRASED target question with certainty
Statement 2 is NOT SUFFICIENT
Statements 1 and 2 combined
Statement 1 tells us that x = 50
Statement 2 tells us that y = 35
So,
x + y = 50 + 35 = 85
Since we can answer the
REPHRASED target question with certainty, the combined statements are SUFFICIENT
Answer: C
Cheers,
Brent
