To give a 21 kg child a ride, two teenagers pull on a 3.4 kg sled with ropes, as indicated in the figure.

To give a 21 kg child a ride, two teenagers pull on a 3.4 kg sled with ropes, as indicated in the figure. Both teenagers pull with a force of F = 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.