Question

Given:  is parallel to
m∠ABC = 70°
m∠CED = 30°

Prove: m∠BEC = 40°

Statement	Justification
is parallel to	Given
m∠ABC = 70°	Given
m∠CED = 30°	Given
m∠ABC = m∠BED	Corresponding Angles Theorem
m∠BEC + m∠CED = m∠BED	Angle Addition Postulate
m∠BEC = 40°	Subtraction Property of Equality

Which of the following accurately completes the missing statement and justification of the two-column proof?

m∠BEC + 30° =70°; Substitution Property of Equality m∠BEC + 30° = 70°; Addition Property of Equality m∠BEC + 40° = 70°; Substitution Property of Equality m∠BEC + 40° = 70°; Addition Property of Equality

Answer 1

[Given]

[Given]

[Corresponding Angles Theorem]

[Angle Addition Postulate]

Since we know that, and , therefore substituting the values we get

[Substitution Property of Equality]

[Subtraction Property of Equality]

Therefore,

The correct option is

[Substitution Property of Equality]