The difference between 90 and 79 is: 
The difference between 39 and 29 is: 
The difference between 99 and 79 is: 
The difference between 90 and 70 is: 
The difference between 90 and 79 is: 
The difference between 90 and 39 is: 
The difference between 99 and 78 is: 
The difference between 90 and 79 is: 