Question 1065217
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Flying against the wind, a jet travels 5670 mi in 7 hours. Flying with the wind, the same jet travels 11,790 mi in 9 hours. 
What is the rate of the jet in still air and what is the rate of the wind? 
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<pre>
Let u be the speed of the plane at no wind (in mph),
and "v" be the speed of the wind.

Then

{{{5670/7}}} = u - v    (1)   (speed flying with the wind)

{{{11790/9}}} = u + v   (2)   (speed flying against the wind)

Simplify:


u - v =  810,           (1')
u + v = 1310.           (2')

Add the two equations (1') and (2'). You will get

2u = 2120  ---->  u = {{{2120/2}}} = 1060 mph.

Then from (2') v = 1310 - u = 1310 - 1060 = 250 mph.

Thus the formal answer is: the speed of the plane is 1060 mph, the speed of wind is 250 mph.


     Now, the speed of wind of 250 mph is more that a strongest hurricane,
          so I don't know who invented this problem.
</pre>

As well as I don't know for whom I solved it and for what.



Usually I have good advises for people who come to the forum with similar problems,

but in this case, I don't know what to do and how to communicate with them.