The difference between 68 and 55 is: 
The difference between 77 and 21 is: 
The difference between 68 and 55 is: 
The difference between 68 and 51 is: 
The difference between 88 and 55 is: 
The difference between 68 and 15 is: 
The difference between 71 and 58 is: 
The difference between 68 and 55 is: 