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In the figure, the exterior angle is $(3 x + 10)$ ° and the interior opposite angles are $(x + 20)$ ° and 50°. Find $x$ .

Class 9Exterior Angle of a TriangleGeometry — Lines and Angles

A40
B15
C20
D30

Step-by-Step Solution

3 x + 10 = (x + 20) + 50 = x + 70

. So

2 x = 60

and

x = 30

. Check: 100° = 50° + 50°.

Answer: D) 30

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