A man is trying to get his car out of mud on the shoulder of a road. He ties one end of a rope tightly around the front bumper and the other end tightly around a utility pole a distance d away. He then pushes sideways on the rope at its midpoint with a force F, displacing the center of the rope x from its previous position, and the car barely moves. What is the magnitude of the force on the car from the rope? (The rope stretches somewhat.) State your answer in terms of the given variables.