The difference between 90 and 90 is: 
The difference between 61 and 23 is: 
The difference between 99 and 90 is: 
The difference between 90 and 90 is: 
The difference between 90 and 90 is: 
The difference between 90 and 20 is: 
The difference between 93 and 97 is: 
The difference between 90 and 90 is: 