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∠1and ​∠2​ are a linear pair, and ​∠2​ and ​∠3​ are vertical angles. m∠1=(3y+10)∘ and ​m∠3=(5y−30)∘. What is m∠2?

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6 votes

Answer:


m\angle 2=95^(\circ)

Explanation:

It is given that ∠1 and ​∠2​ are a linear pair. So, there sum is 180 degrees.


m\angle 1+m\angle 2=180^(\circ) ...(1)

∠2​ and ​∠3​ are vertical angles. So, both are equal.


m\angle 2=m\angle 3 ...(2)

From (1) and (2), we get


m\angle 1+m\angle 3=180^(\circ)

Substitute
m\angle 1=(3y+10)^(\circ) and
m\angle 3=(5y-30)^(\circ) in the above equation.


(3y+10)^(\circ)+(5y-30)^(\circ)=180^(\circ)


(8y-20)^(\circ)=180^(\circ)


8y-20=180


8y=180+20

Divide both sides by 8.


y=(200)/(8)


y=25

The value of y is 25.

Using equation (2), we get


m\angle 2=m\angle 3=(5y-30)^(\circ)

Substitute y=25.


m\angle 2=(5(25)-30)^(\circ)


m\angle 2=(125-30)^(\circ)


m\angle 2=95^(\circ)

Therefore,
m\angle 2=95^(\circ).

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