Question 1143533
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Let u = the aircraft speed at no wind and v = the speed of the wind.


Then the speed of the aircraft flying with the wind is (u+v) miles per hour,

while its speed flying against the wind is (u-v) miles per hour.


From the condition, you have these equations


    u + v = {{{540/3}}} = 180  mph     (1)

    u - v = {{{540/6}}} =  90  mph     (2)


Subtract eq(2) from eq(1). You will get


    2v = 180 - 90 = 90 mph

     v            = 90/2 = 45 mph.


<U>ANSWER</U>.  The speed of the wind is 45 miles per hour.
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Solved.