Question 1196918
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Hi  
Flying against the wind, an airplane travels 1920 kilometers in 3 hours:  {{{s - w}}} 
Flying with the wind, the same plane travels 3520 kilometers in 4 hours:  {{{s + w}}}
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
 {{{880-760}}} = 120 km/hr, the rate of the wind
Wish You the Best in your Studies.
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