Question

I need this problem solved real quick

Answer 1

Let's take this problem step-by-step:

The ;unlabeled angle' adjacent to the 'outside angle of measure 78°'

  ⇒ is on a straight line

     ⇒ sum of angle measure = 180 degrees

       $unlabeled_.angle+78 = 180\\unlabeled_.angle = 102$

Now we know:

 ⇒ sum of all angles in a triangle ⇒ 180°

Let's put that in equation form and solve:

  $x + 102 + 57=180\\x + 159=180\\x = 21$

Answer: 21°

Hope that helps!

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