The difference between 91 and 67 is: 
The difference between 90 and 23 is: 
The difference between 99 and 67 is: 
The difference between 91 and 60 is: 
The difference between 81 and 67 is: 
The difference between 91 and 57 is: 
The difference between 97 and 63 is: 
The difference between 91 and 67 is: 