Good night, how can I solve this? It's about forces

28. A 85 N child sits motionless on a 45 N tire swing. a. What is the mass of the child? b. What is the tension of the rope that holds the child and the tire up? 29. A 0.15 kg acorn falls from a tree with an acceleration of 8.9 m/s . Air resistance is present. a. What is the weight of the acorn? b. What is the net force acting on the acorn? c. What is the drag force (aka air resistance) acting on the acorn? 30. Two forces are applied to an air hockey puck on the frictionless table, a 173 N force and a 2 72 N force. a. What is the net force acting on the puck if the forces are applied in the same direction? b. What is the net force acting on the puck if the forces are applied in opposite directions