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 perimeter of Jesse's room. We know that the perimeter is the sum of all the sides of a rectangle. In this case, we need to find the sum of the length and width of the room. The length is x feet and the width is w feet, so the perimeter is x + 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 from the length. The length is x feet and the width is w feet, so the room is x - w feet longer than it is wide. 

Therefore, the answer (symbolic expression) is: 

x - w