A.6 Which is correct?

Angles

How can you find the measure of ∠1.


Alex's "Linear Angle" Method
I think the bottom three angles add to 180° because they form a line.
I solved for the measure of ∠1.
I notice that the measure of ∠1 and ∠B are the same.
55° + 50° + m∠1 = 180°
105° + m∠1 = 180°
m∠1 = 75°
m∠1 = m∠B