The difference between 68 and 15 is: 
The difference between 88 and 13 is: 
The difference between 67 and 15 is: 
The difference between 68 and 16 is: 
The difference between 88 and 15 is: 
The difference between 68 and 55 is: 
The difference between 72 and 19 is: 
The difference between 68 and 15 is: 