The difference between 81 and 15 is: 
The difference between 71 and 37 is: 
The difference between 87 and 15 is: 
The difference between 81 and 10 is: 
The difference between 51 and 15 is: 
The difference between 81 and 45 is: 
The difference between 87 and 11 is: 
The difference between 81 and 15 is: 