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The answer is -8 because -4x2 is -8
        
                    
             
        
        
        
Locker 1 has more storage space because it has a greater volume.
The volume of locker 1 is 8,640 (48x15x12)
The volume of locker 2 is 7,200 (60x10x12) 
I hope this helps. 
        
             
        
        
        
30, 6+9= 15+4= 19+1= 20+10= 30
        
                    
             
        
        
        
I would tell you how to do it but its a very hard thing to explain