David did w more push-ups than Zachary in gym class today. If David did x push-ups How many push-ups did Zachary and David do altogether?
First, we need to find out how many push-ups David did. We know that David did w more push-ups than Zachary, and we know that David did x push-ups. This means that Zachary must have done x - w push-ups. 

Now, we need to find out how many push-ups Zachary and David did altogether. To do this, we need to add the number of push-ups that Zachary did to the number of push-ups that David did. We know that David did x push-ups, and we know that Zachary did x - w push-ups. This means that Zachary and David must have done x + (x - w) push-ups. 

However, we can simplify this expression. We know that x - w is the same as x + (-w). This means that we can rewrite x + (x - w) as x + x + (-w), which is the same as 2x + (-w). 

Therefore, the answer (symbolic expression) is: 

2x + (-w)