David did 27 push-ups in gym class today. David did 14 more push-ups than Zachary. How many push-ups did Zachary and David do altogether?
David did 27 push-ups. 
Zachary did 14 more than David. 
That means Zachary did 41 push-ups. 

Now we can add 27 and 41 to get the total number of push-ups done by both boys: 

27 + 41 = 68