At the zoo, a cage had w snakes and x alligators. If y alligators were hiding How many alligators were not hiding?
First, we need to find out how many alligators were hiding. We know that y alligators were hiding, so the number of alligators that were not hiding must be x - y. 

Now, we need to find out how many alligators were not hiding. We know that the number of alligators that were not hiding is x - y, so the number of alligators that were not hiding is (x - y). 

This means that the answer (symbolic expression) is: 

x - y