The correct statement that completes the proof is:
Transitive Property of Equality
So the completed proof would look like this:
Statements Reasons
- m∡A+m∡C=180°
- Linear Pairs are supplementary
- m∡A=m∡E
2. Transitive Property of Equality - m∡E+m∡C=180°
3. Substitution - ∠E and ∠C are supplementary
4. Definition of Supplementary Angles