A 70.0 kg skydiver falls towards the earth. The force due to air resistance is 1200 N. What is the acceleration of the skydiver?

The force of gravity on the skydiver is

F (g) = (mass) x (gravity)

F (g) = (70 kg) x (9.8 m/s²)

F (g) = 686 Newtons, downward (her "weight")

If, through some mysterious process, the force due to air resistance acting on her is 1,200 Newtons upward, then the net force on the skydiver is

F (net) = (686 N down) + (1,200 N up)

F (net) = 514 Newtons, up

The skydiver is accelerating UP, at 7.34 m/s².

I have no idea how this could actually happen in the real world, but the Math and Physics are bullet-proof here.