The difference between 90 and 71 is: 
The difference between 81 and 77 is: 
The difference between 93 and 71 is: 
The difference between 90 and 70 is: 
The difference between 90 and 71 is: 
The difference between 90 and 21 is: 
The difference between 99 and 70 is: 
The difference between 90 and 71 is: 