Question

∠A

and ​
∠B
​ are vertical angles with 
m∠A=x
and 
m∠B=4x−30
.
What is
m∠A
?

Answer 1

m∠A=10°

Explanation:

we know that

Vertical angles are the angles opposite each other when two lines cross. The angles are congruent.

so

In this problem we have

m∠A=m∠B

substitute the given values

`x=4x-30`

Solve for x

`4x-x=30\\3x=30\\x=10`

Find the measure of angle A

m∠A=x

substitute the value of x

m∠A=10°