Question 1164594
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Let "u" be the plane speed in still air;  "v" be the speed of the wind.


Then from the condition, effective rate with the wind is

    u + v = {{{7070/7}}} = 1010  km/h


Effective rate against the wind is

     u -v = {{{3060/6}}} = 510  km/h


Add the two equations  (1)  and  (2)  to get

    2u    = 1520;  

     u    = 1520/2 = 760.


Then from equation (1),

     v    = 1010 - 760 = 250.


<U>ANSWER</U>.  The plane speed in the still air is  760 km/h.  The wind speed is 250 km/h.
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Solved.