Question

50 POINTS!!!!!!!!!!! I need help pleaseeeeeee

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Question
What is the measure of ∠B?
Triangle A B C with ray A G through point C and angle measures A = 3x, B = 4x, and exterior angle B C G = 10x minus 45.

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Responses

60∘60 degrees

15∘15 degrees

45∘45 degrees

105∘

Answer 1

∠ B = 60°

Explanation:

the exterior angle of a triangle is equal to the sum of the 2 opposite interior angles.

10x - 45 is an exterior angle of the triangle , then

10x - 45 = 3x + 4x = 7x ( subtract 7x from both sides )

3x - 45 = 0 ( add 45 to both sides )

3x = 45 ( divide both sides by 3 )

x = 15

Then

∠ B = 4x = 4 × 15 = 60°