According to Newton's third law of motion, when two objects collide, they exert equal and opposite forces on each other. This means that the force exerted by the yellow bumper car on the green bumper car is equal in magnitude to the force exerted by the green bumper car on the yellow bumper car, but in the opposite direction.
Given that the green bumper car exerts a force of 320 N on the yellow bumper car during the collision, the yellow bumper car will exert an equal and opposite force of 320 N on the green bumper car.
Therefore, the force exerted by the yellow bumper car on the green bumper car during the collision is 320 N (in the direction opposite to that of the force exerted by the green bumper car).