The difference between 90 and 21 is: 
The difference between 77 and 20 is: 
The difference between 96 and 21 is: 
The difference between 90 and 20 is: 
The difference between 70 and 21 is: 
The difference between 90 and 11 is: 
The difference between 99 and 20 is: 
The difference between 90 and 21 is: 