The difference between 50 and 21 is: 
The difference between 52 and 15 is: 
The difference between 56 and 21 is: 
The difference between 50 and 20 is: 
The difference between 90 and 21 is: 
The difference between 50 and 41 is: 
The difference between 59 and 20 is: 
The difference between 50 and 21 is: 