Adding a negative number is the same as subtracting a positive number. So 2315.5 - 3166.75 = -851.25
        
             
        
        
        
1679/7
=239.85...
Rounds to 240
So average rate is 240
        
             
        
        
        
An example of unit price in germany is the electricity
        
             
        
        
        
Because there nobody that teaches them how to do math