<PRE><B>Question 81379</B>
With the wind, the air will aid the airplane

Let speed of Air = A
Speed of plane  = 100

Speed With wind = 100+A
Speed Against wind = 100-A

Since Time is Constant and we know Distance = Speed x Time

{{{Distance_1/Speed_1}}} = {{{Distance_2/Speed_2}}}

36/(100+A) = 12/(100-A)

Dividing both sides with 12
3/(100+A) = 1/(100-A)

Cross Multiplying

300-3A = 100+A
200 = 4A
A = 50

So speed of air = 50mph
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