GAUSS7 2012 Problem 5

Past Contests GAUSS7 GAUSS (GR. 7) - 2012
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1

Two straight lines intersect as shown. The measure of the angle marked \Box is

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Answer Choices
A. 60^\circ
B. 120^\circ
C. 30^\circ
D. 300^\circ
E. 180^\circ