This is my work hope this helps.
 
        
                    
             
        
        
        
Answer:
C
Step-by-step explanation:
If you add the first equation up you get 2z+6 by combining like terms 
if you see A a is equal to 3z+6 so a doesn’t work
If you look at B b is equal to z+12 so b doesn’t work 
finally C if you distibute it out you get 2(z)+2(3) which equal 2z+6 which works
C
 
        
             
        
        
        
Answer:

Step-by-step explanation:
 
        
             
        
        
        
Answer:
2/7
Step-by-step explanation:
This is because the slope is positive so that gets rid of both of the negatives, and the line is not straight but if the line was horizontally straight then your slope would be zero. So I just did process of elimination.