Question

Given: A, C, and F are collinear

Answer 1

m∠x+m∠r+m∠y=180° (angles in a triangle add to 180°)

m∠r+m∠s=180° (angles that form a linear pair add to 180°)

m∠x+m∠r+m∠y=m∠r+m∠s (Transitive property of equality)

m∠x+m∠y=m∠s (subtraction property of equality)

m∠s=m∠x+m∠y (symmetric property of equality)