Two children push on opposite sides of a door during play. Both push horizontally and perpendicular to the surface of the door. One child pushes with a force of 19.5 N at a distance of 0.575 m from the hinges, and the second child pushes at a distance of 0.475 m. What is the magnitude of the force (in N) the second child must exert to keep the door from moving? Assume friction is negligible.