Question

What is the missing justification?

Answer 1

Transitive property:

If a = b, and b = c, then a = c.

Here you are doing it with congruence of angles.

Strictly speaking, the correct reason is not the transitive property of equality since the transitive property applies to equality. In this case, it's a theorem for congruence of angles. Since that theorem is not mentioned, the best answer here is "transitive property."

Answer 2

Transitive property is your answer

if ∠A ≅ ∠C, and ∠C ≅ ∠B then, ∠A ≅ ∠B

hope this helps