Well both a and b are correct  because angles 4,6, and 7 are all congruent.
4 and 6 are alternate interior angles, 4 and 7 are corresponding angles, and 6 and 7 are vertical angles all equaling the same degree. so i would go with B only because it backs it up with proof and a is just an observation.
        
                    
             
        
        
        
1. Is the actual equation, so this is Given
2. removing the parenthesis is the Distributive Property
3. Combining like terms.
4. They add 6x to both sides, this would be the Addition Property of Equality
5. Subtract 4 from both sides, this is the Subtraction Property of Equality.
6. Divide both sides by 8, this would be the Division Property of Equality.
 
        
                    
             
        
        
        
Well it sounds like a trick question but the answer is simple! If she runs 90 meters per minute, In one minute she will run 90 meters. 
Answer 90
        
             
        
        
        
Answer:
Step-by-step explanation:
4 lines of symmetry
 
        
                    
             
        
        
        
Answer: 24
Step-by-step explanation:
m - 15 + 15 = 9 + 15
m = 24