How can you find the measure of ∠1.

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