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If  and  , find the measures of each numbered angle.  Then explain how you found each angle, citing definitions and conjectures that support your steps. 

Since two of the lines are parallel, their alternate interior angles and corresponding angles are equal to each other.

Angles 1, 2, and 3 form a straight angle, as do angles 4 and 5 and angles 6 and 7.

2 horizontal parallel lines, are crossed by 2 transversals. The transversals intersect on the upper parallel line. Angles are labeled as follows: Upper intersection of 3 lines: interior left, 1, interior middle, 2, interior right, 3. Lower left intersection of 2 lines: interior left, 4, interior right, 5. Lower right intersection of 2 lines: interior left, 6, interior right, 7.