The difference between 91 and 18 is: 
The difference between 93 and 50 is: 
The difference between 99 and 18 is: 
The difference between 91 and 10 is: 
The difference between 71 and 18 is: 
The difference between 91 and 28 is: 
The difference between 93 and 10 is: 
The difference between 91 and 18 is: 