Answer:
o = 54
Explanation:
The angle sum theorem tells you the sum of angles in a triangle is 180°. The definition of a linear pair tells you the two angles of a linear pair total 180°. Together, these relations tell you that an exterior angle of a triangle is equal to the sum of the remote interior angles.
In this geometry, the angle marked 78° is exterior to the left-side triangle. That means ...
78° = o° +24°
o° = 78° -24° = 54°
The value of 'o' is 54.
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Additional comment
n° is the supplement of 78°, so is 102°.
m° is the difference between 102° and 22°, so is 80°.