Answer:
1.75
Step-by-step explanation:
If a  and b are two numbers, then their arithmetic mean is 

Given:

Divide this equation by 10:

Now, divide it by 2:

 
        
             
        
        
        
Answer:
 I don't know
Step-by-step explanation:
if don't know
 
        
             
        
        
        
I think it is 10.
hope this helps!!! :D