Pressure and lift force on a wing

[physixnot4me]

An airplane has a mass of 1.60-10^4 kg and each wing has an area of 40.0m^2. During level flight, the pressure on the lower wing surface is 7.00-10^4 Pa. Determine the LIFT FORCE on the plane. Is it sufficient to lift the plane?

part is what concerns me: if it is in level flight, the net force is zero

How do I go about answering this question... leading me in the right direction would be very helpful =) Big thanks!

 

[Astronuc]

Force (N) = Pressure (N/m²) * Area (m²)

and the upward force must equal the weight of the plane.

For a plane to 'fly' the pressure above the wing must be lower than the pressure below the wing, so that the net force on the wing is upward and equal to the weight of the plane.