For this equation, let b equal the cost per box. 
b=$100/5
        
             
        
        
        
If you looked it up online you could find it. look on safari
        
                    
             
        
        
        
Answer: He should have used 13 instead of 13i
Step-by-step explanation:
 
        
                    
             
        
        
        
Answer:
b for top and c for botam
Step-by-step explanation: