Answer:
Option C. 
Step-by-step explanation:
The top box must ALWAYS contain the answer to the problem. 
 
        
                    
             
        
        
        
The answer is B. -7m+12.
First distribute the -2 to 6m and -5.
5m-2(6m-5)+2
5m+(-2*6m)+(-2*-5)+2
5m+-12m+10+2
After that, combine the like terms.
5m+-12m+10+2
-5m+-12m=-7m
10+2=12
The simplified expression is -7m+12.
 
        
             
        
        
        
In order to find b1 from your formula stated we need to do few calculations
A=hb1+hb2, as you wee I multiply h with both bases( b1 and b2)
I will subtract hb2 from both sides
hb1=A-hb2
now I will divide my new expression by h
b1=(A-hb2)/h
        
                    
             
        
        
        
52/6 in simplest form is 8 2/3
I got the answer 8 2/3 because 6 can go into 52 8 times and there is a remainder the remainder that I got was 4 . I'll put the remainder over the denominator which is 6. So right now I would have 8 4/6 but this fraction can be simplied again by 2 so the final answer is 8 2/3