Answer:
See Below.
Explanation:
1) Given:
2) Definition of Linear Pair:
3) Given:
4) Given:
5) Substitution Property:
6) Combine Like Terms:
7) Subtraction Property of Equality (subtract 20 from both sides):
8) Division Properety of Equality (divide both sides by 8):
9) Given (this step is optional. You don’t have to include this):
10) Substitution:
11) Multiplication:
12) Addition: