Hi Flying against the wind, an airplane travels 1920 kilometers in 3 hours:Flying with the wind, the same plane travels 3520 kilometers in 4 hours: D=rt 0r r = D/t Question States: s - w = 1920/3 = 640m km/hr s + w = 3520/4 = 880 km/hr | Solving by eliminating w 2s = 1520 km/hr s = 760 km/hr , the the rate of the plane in still air = 120 km/hr, the rate of the wind Wish You the Best in your Studies.