Free body diagram:
When the skydiver opens her parachute, the lift force (617 N) and air resistance (20 N) act in the upward direction and the weight (mg) acts downwards (towards the center of the earth).
The net force acting on the skydiver is given as,
Here, m is the mass of the skydiver (65 kg) and g is the acceleration due to the earth's gravity (9.8 m/s²).
Substituting all known values,
Therefore, no net force (0N) acting on the skydiver.