Answer:
2w +76 = 180
Explanation:
The relations that help you write the necessary equation are ...
- vertical angles are congruent
- a straight angle measures 180°
- an angle is the sum of its parts
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You need to be able to recognize two kinds of angles here.
vertical angle
Vertical angles are created where two lines cross. The angles that share a vertex and are formed from opposite rays are called "vertical angles." They do not share a side. Vertical angles are congruent.
In this diagram, the unmarked angles between w° and 76° have measure w°, because they are congruent with the vertical angle opposite the point of intersection.
The unmarked angle between the ones marked w° has measure 76°, because it is congruent with the vertical angle marked 76°.
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straight angle
A straight angle is a straight line. Its vertex can be any point on the line. It always has a measure of 180°.
Here, the straight angles of interest all have the same vertex. They are each divided into 3 parts. Two of those parts are angles marked (or equal to) w°, and one of those parts is the angle marked (or equal to) 76°. The sum of the parts is 180°, which is where you get the equation you need to write:
w° +w° +76° = 180°
Of course, you can simplify this to ...
2w +76 = 180
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Additional comment
Solving the equation gives you the value of w°.
2w = 180 -76 = 104
w = 104/2 = 52
The angles marked w° have measure 52°.