Question

find x..............

Answer 1

Angle ACB=180°-100°=>80°

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ANGLE SUM PROPERTY=180°

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Angle A+Angle B+Angle C=180°

30°+x+80°=180°
110°+x=180°
x=180°-110°
x=70°

Answer 2

hola ,

the exterior angle=sum of the two interior angle.

100=30+x
30+x=100
x=100-30
x=70

hence,
x is 70
as we know that sum of the two interior angles equal to the exterior angle.
so,
x+30=100
70+30=100
100=100
(verified)