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9-9.

If $m\angle5 = 53º$ and  $m\angle7 = 125º$, find the measures of each numbered angle.  Then explain how you found each angle, citing definitions and conjectures that support your steps.  Homework Help ✎

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.

$m∠7 = m∠1 + m∠2$