Answer/Step-by-step explanation:
STATEMENT ====> REASONS
1. m<AOB = 180° ==> 1. Definition of straight angle
2. m<AOF + m<FOG + m<GOB = m<AOB ==> 2. Angle Addition Postulate
3. (5x - 15)° + 90° + 2x = 180° ==> 3. Substitution
4. Solve as algebra to get x
5x - 15 + 90 + 2x = 180
Collect like terms
5x + 2x - 15 + 90 = 180
7x + 75 = 180
Subtract 75 from both sides
7x + 75 - 75= 180 - 75
7x = 105
Divide both sides by 7
7x/7 = 105/7
x = 15 ===> 4. Algebra
