Bunuel wrote:

What is the value of y in the figure above?

(A) 70

(B) 80

(C) 90

(D) 100

(E) 110

We can create the following equations:

25 + y + x = 180

And

45 + x + 180 - y = 180

45 + x - y = 0

Adding the equations together we have:

70 + 2x = 180

2x = 110

x = 55

Since 45 + x = y, y = 100.

Alternate Solution:

The large triangle’s angle measures sum to 180 degrees. Thus, we have:

25 + 45 + 2x = 180

2x = 110

x = 55

The bottom left triangle’s angle measures sum to 180:

25 + 55 + y = 180

80 + y = 180

y = 100

Answer: D

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Jeffery Miller

Head of GMAT Instruction

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