Identify the correct justification for each step, given that m∠1≅m∠2, m∠3=100°, and ∠1 and ∠EBC are supplementary. 1. ∠1 and ∠EBC are supplementary

2. m∠1+m∠EBC=180°
3. m∠2+m∠3=m∠EBC
4. m∠1+m∠2+m∠3=180°
5. m∠1≅m∠2
6. m∠1+m∠1+m∠3=180°
7. m∠3=100°
8. m∠1+m∠1+100°=180°
9. 2(m∠1)+100°=180°
10. 2(m∠1)=80°
11. m∠1=40°

Answers:

A. 1. Given
2. Def. of Supp. ∠s
3. Add. Prop. of =
4. Subst. Prop. of =
5. Given
6. Subst. Prop. of =
7. Given
8. Subst. Prop. of =
9. Simplify
10. Subt. Prop. of =
11. Mult. Prop. of =

B. 1. Given
2. Def. of Supp. ∠s
3. ∠ Add. Post.
4. Subst. Prop. of =
5. Given
6. Add. Prop. of =
7. Given
8.Add. Prop. of =
9. Simplify
10. Add. Prop. of =
11. Mult. Prop. of =

C. 1. Given
2. Lin. Pair Thm.
3. ∠ Add. Post.
4. Subst. Prop. of =
5. Vert. ∠s Thm.
6. Subst. Prop. of =
7. Given
8. Subst. Prop. of =
9. Simplify
10. Subt. Prop. of =
11. Div. Prop. of =

D. 1. Given
2. Def. of Supp. ∠s
3. ∠ Add. Post.
4. Subst. Prop. of =
5. Given
6. Subst. Prop. of =
7. Given
8. Subst. Prop. of =
9. Simplify
10. Subt. Prop. of =
11. Div. Prop. of =