Aand \angle b∠b are vertical angles. if m\angle a=(4x+23)^{\circ}∠a=(4x+23)
∘
and m\angle b=(5x-7)^{\circ}∠b=(5x−7)
∘
, then find the measure of \angle b∠b.

m∠B=143°

Step-by-step explanation:

we know that

Vertical Angles are the angles opposite each other when two lines cross. They are always equal

so

In this problem we have that

m∠A=m∠B ----> by vertical angles

substitute the given values and solve for x

Find the measure of angle B

m∠B=(5x-7)°

substitute the value of x

m∠B=(5(30)-7)°

m∠B=143°

i think the answer is b