It's because a tenth means that you've divided it by 10. So if it's 20, it means you're multiplying tenths by 20, leaving you with 2 wholes. 
For example, you have 2 cakes and you cut each into 10 slices, the slices are each one tenth of the whole cake, and in total there are 20 tenths. 
 
        
                    
             
        
        
        
I don't know which one is underlined so I will write it out in words.
One million seven hundred and eleven thousand and seven hundred ninety-nine.
Hope I helped :)
 
        
             
        
        
        
Correct answer is y = 3x + 1
the answer on D has been cut off..
        
             
        
        
        
don't know if this might help but here 
Step-by-step explanation:
(−∞,∞),{y|y∈R}