I dont know if this is right but the answer to 2(12+8x)-3(4x-9) might be 4x+51?
        
                    
             
        
        
        
Answer:
126
Step-by-step explanation:
 
        
             
        
        
        
Answer:
Last one 
Step-by-step explanation:
 
        
                    
             
        
        
        
288 books.
8 books in 5 minutes.
60 minutes in one hour.
5 * 12 = 60
60 minutes * 3 = 3 hours
8 * 12 = 96
96 books in one hour.
96 * 3 = 288
288 books in three hours. 
        
                    
             
        
        
        
Answer:
19)  (  )^2 =
)^2 = 
20) - = -81
 = -81 
21)   = 16
 = 16
Step-by-step explanation:
The only wrong ones are 
19)  (  )^2 =
)^2 = 
20) - = -81 ... negative is not inside a parenthesis that's why it is still negative
 = -81 ... negative is not inside a parenthesis that's why it is still negative
21) you can add another way is  = 16
 = 16
Everything else looks good.  Great job!