I think the answer is 12 because 3 times 4 is 12
        
                    
             
        
        
        
Answer: The answer is F.
Step-by-step explanation:
1.) The first equation represents how the spiral notebook has 30 more pages than the the memo book, and how subtracting the memo book's pages would result with 30.
2.) The second equation represents how the total number of pages in 3 spiral notebooks plus 5 memo books would result in 810 total pages.
 
        
             
        
        
        
Answer:  1 hour 20 minutes
Step-by-step explanation:
Given : The old machine could shred a truckload of paper in 4 hours.
Rate of work done by old machine = 
 The new machine could shred the same truckload in 2 hours. 
Rate of work done by new machine = 
Let 't' be the time taken by both of them working together , then we have the following equation:-

Since 1 hour = 60 minutes
Then, 
Hence, it will take 1 hour 20 minutes to shred the same truckload of paper if Ron runs both shredders at the same time.
 
        
             
        
        
        
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That is the answer for your problem
        
             
        
        
        
Step-by-step explanation:
we have
5x+4=2x+9
5x-2x=9+4
3x=13
x=13/3