The difference between 90 and 31 is: 
The difference between 77 and 10 is: 
The difference between 97 and 31 is: 
The difference between 90 and 30 is: 
The difference between 90 and 31 is: 
The difference between 90 and 71 is: 
The difference between 99 and 30 is: 
The difference between 90 and 31 is: 