Question

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

Answer 1

Answer:

m∠A=10°

Step-by-step 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°