Zachary did 22 push-ups in gym class today. David did 25 more push-ups than Zachary. John did 39 push-ups less than david. How many push-ups did David do?
Zachary did 22 push-ups. 
David did 25 more push-ups than Zachary. 
John did 39 push-ups less than David. 

That means that David did 25 + 22 = 47 push-ups.