The difference between 39 and 31 is: 
The difference between 87 and 57 is: 
The difference between 39 and 31 is: 
The difference between 39 and 35 is: 
The difference between 59 and 31 is: 
The difference between 39 and 21 is: 
The difference between 41 and 33 is: 
The difference between 39 and 31 is: 