I think the answer is 9
It's a smaller version of the other figure. 
21/3=7
27/3=9
        
             
        
        
        
What do you think and what have you previously learned on the subject?
        
             
        
        
        
It would be 6.5. The 5 after the decimal would stay the same since the number after it isn't greater than 5
        
                    
             
        
        
        
9 sheets of paper I believe 
Have a good day :)