Zachary did 24 push-ups in gym class today. David did 30 more push-ups than Zachary. John did 22 push-ups less than David. How many push-ups did John do?
Zachary did 24 push-ups. 
David did 30 more push-ups than Zachary. 
John did 22 push-ups less than David. 

That means that David did 54 push-ups. 

Now we can solve for John: 

John did 54 - 22 = 32 push-ups.