6.8,6.827,6.86,6.9
1.2,1.203,12.03, 12.301,12.31
        
             
        
        
        
Answer:
-3
Step-by-step explanation:
-20-15+30+2
-35+32
-3
 
        
             
        
        
        
Answer:
The conclusion is invalid.
The required diagram is shown below:
Step-by-step explanation:
Consider the provided statement.
Great tennis players use Hexrackets. Therefore, if you use a Hexracket, you are a great tennis player. 
From the above statement we can concluded that Great tennis players use Hexrackets. But it may be possible that some people who use a haxracket are not great tennis player.
Therefore, the conclusion is invalid.
The required diagram is shown below: