The difference between 20 and 13 is: 
The difference between 81 and 76 is: 
The difference between 25 and 13 is: 
The difference between 20 and 10 is: 
The difference between 40 and 13 is: 
The difference between 20 and 13 is: 
The difference between 28 and 11 is: 
The difference between 20 and 13 is: 