Jesse's room is w feet wide and x feet long. How much longer is her room than it is wide?
First, we need to find the width of the room. We know that the room is w feet wide and x feet long. This means that the width of the room must be w feet. 

Now, we need to find out how much longer the room is than it is wide. To do this, we need to subtract the width of the room from the length of the room. We know that the width of the room is w feet, so the length of the room must be x - w feet. 

This means that the room is (x - w) feet longer than it is wide.

Therefore, the answer (symbolic expression) is: 

x - w