1. The problem statement, all variables and given/known data A small plane flies at 120km/h over the end of a runway along the axis of the runway. There is a crosswind, exactly 90 degrees to the direction of the runway, blowing at 50km/h. The speed of the plane with respect to the air is: 130km/h 50km/h 120km/h need more info 70km/h 2. Relevant equations 3. The attempt at a solution I set up the equation: V(p/g) ( plane respect to ground ) = V(p/a) (plane respect to air) + V(a/g) (air respect to ground) p/g = 120 a/g =50 120 = 50 +x sqrt(120^2 - 50^2) = x ? this gives 109 km/h though which is not a choice, did I do something wrong?