The two-column proof below describes the statements and reasons for proving that corresponding angles are congruent: What is the missing statement for step 6?

StepStatementsReasons
1segment UV is parallel to segment WZGiven
2Points S, Q, R, and T all lie on the same line. Given
3m∠SQT = 180°Definition of a Straight Angle
4m∠SQV + m∠VQT = m∠SQTAngle Addition Postulate
5m∠SQV + m∠VQT = 180°Substitution Property of Equality
6 Same-Side Interior Angles Theorem
7m∠SQV + m∠VQT = m∠VQT + m∠ZRSSubstitution Property of Equality
8m∠SQV + m∠VQT − m∠VQT = m∠VQT + m∠ZRS − m∠VQT
m∠SQV = m∠ZRSSubtraction Property of Equality
∠SQV ≅ ∠ZRSDefinition of Congruency