The difference between 91 and 19 is: 
The difference between 57 and 29 is: 
The difference between 99 and 19 is: 
The difference between 91 and 10 is: 
The difference between 81 and 19 is: 
The difference between 91 and 89 is: 
The difference between 93 and 11 is: 
The difference between 91 and 19 is: 