David did 697 more push-ups than Zachary in gym class today. If David did 76 push-ups How many push-ups did Zachary and David do altogether?
1) David did 697 more push-ups than Zachary. 
2) If David did 76 push-ups, then we can say that Zachary did -697 + 76 = -621 push-ups. 
3) So, David and Zachary did 76 + (-621) = -545 push-ups altogether.