Given: m24+ m27 = 180°
Prove: c || d

Answer:
Given: c | | d, m 4 = m 5
Prove: m 7 = m 8
1. c||d, m∠4=m∠5
GIVEN
2. m∠4 = m∠7
If lines ||, alternate interior angles are equal.
3. m∠5 = m∠8
Vertical angles are equal.
4. m∠7 = m∠8
Substitution
Step-by-step explanation: