The difference between 17 and 15 is: 
The difference between 93 and 40 is: 
The difference between 18 and 15 is: 
The difference between 17 and 10 is: 
The difference between 77 and 15 is: 
The difference between 17 and 15 is: 
The difference between 20 and 18 is: 
The difference between 17 and 15 is: 