The difference between 28 and 28 is: 
The difference between 80 and 68 is: 
The difference between 29 and 28 is: 
The difference between 28 and 20 is: 
The difference between 68 and 28 is: 
The difference between 28 and 18 is: 
The difference between 20 and 23 is: 
The difference between 28 and 28 is: 