Answer:
x = 125
Explanation:
Given a heptagon with 60° and 90° angles marked, one marked 2x°, and the remaining angles marked x°, you want o know the value of x.
Sum of angles
The sum of the interior angles of a heptagon is ...
180° × (7 -2) = 900°
Using the given values, this tells us ...
90° +x° +x° +x° +x° +60° +2x° = 900°
6x = 750 . . . . . . . divide by °, subtract 150
x = 125 . . . . . . divide by 6
The value of x is 125.
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Additional comment
The attached figure is drawn with correct angles.
The sum of interior angles of an n-gon is 180°×(n -2).