Answer:
114°
Step-by-step explanation:
The exterior angle is the sum of the remote interior angles.
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setup
(11x +15)° = 60° +6x°
solution
5x = 45 . . . . . . . . . divide by °, subtract 15+6x
x = 9 . . . . . . . . . . divide by 5
The measure of exterior angle KMN is ...
m∠KMN = (11(9) +15)° = 114°
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Additional comment
Both the sum of interior angles and the sum of angles of a linear pair are 180°. If M represents the interior angle at vertex M, then we have ...
60° +6x° +M = 180°
(11x +15)° +M = 180°
Equating these expressions for 180° and subtracting M gives the relation we used above:
(11x +15)° +M = 60° +6x° +M . . . . . equate the two expressions for 180°
(11x +15)° = 60° +6x° . . . . . . . . . . . subtract M
This is also described by "supplements to the same angle are equal."
