The difference between 77 and 57 is: 
The difference between 91 and 39 is: 
The difference between 79 and 57 is: 
The difference between 77 and 56 is: 
The difference between 67 and 57 is: 
The difference between 77 and 67 is: 
The difference between 71 and 52 is: 
The difference between 77 and 57 is: 