Question

If m∠A = m∠B and m∠A + m∠C = ∠D, then
m∠B + m∠C = ∠D.

Which property is shown?

reflexive property
substitution property
symmetric property
transitive property

Answer 1

Think about the problem and what it is doing.

Answer 2

@jahgood

notice how they used the fact that m∠A = m∠B and replaced m<A, with m<B in the equation m∠A + m∠C = ∠D

what's another name for this technique?