To give a 20 kg child a ride, two teenagers pull on a 4.0 kg sled with ropes, as indicated in the figure . Both teenagers pull with a force of 55 N at an angle of 35 relative to the forward direction, which is the direction of motion. In addition, the snow exerts a retarding force on the sled that points opposite to the direction of motion, and has a magnitude of 57 N .Find the acceleration of the sled and child.