The difference between 91 and 68 is: 
The difference between 71 and 12 is: 
The difference between 99 and 68 is: 
The difference between 91 and 60 is: 
The difference between 71 and 68 is: 
The difference between 91 and 58 is: 
The difference between 97 and 64 is: 
The difference between 91 and 68 is: 