Question 1179659
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Flying with the wind, a plane flew 1,120 mi in 4 h. 
Against the wind, the plane required 7 h to fly the same distance. 
Find the rate of the plane in calm air and the rate of the wind.
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<pre>
Let u be the rate of the plane at no wind (in miles per hour)
and v be the rate of the wind (in the same units).


Then the effective rate  of the plane with   the wind is u + v
and  the effective rate of the plane against the wind is u - v.


From the problem, the effective rate of the plane with the wind is the distance of 1120 miles 
divided by the time of 4 hours  {{1120/4}}} = 280 mph.


                  The effective rate of the plane against the wind is the distance of 1120 miles 
divided by the time of 7 hours  {{{1120/7}}} = 160 mph.


So, we have two equations to find 'u' and 'v'

    u + v = 280,    (1)

    u - v = 160.    (2)


To solve, add equations (1) and (2).  The terms 'v' and '-v' will cancel each other, and you will get

    2u = 280 + 160 = 440  --->   u = 440/2 = 220.

Now from equation (1)

     v = 280 - u = 280 - 220 = 60.


<U>ANSWER</U>.  The rate of the plane in still air is 220 mph.  The rate of the wind is 60 mph km/h.
</pre>

Solved.


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My solution produces the same answer as in the post by @mananth, but makes it in clean, clear and correct form,
while calculations in the post by @mananth contradict to each other literally in every line.


We, the tutors, write here our solutions not only to get certain numerical answer.
We write to teach - and, in particular, to teach writing solutions in accurate and clear style.



@mananth repeats his construction of solution with no change for all similar problems on flies
with and against the wind simply because his COMPUTER CODE is written this way.
But his computer code is written in a bad style. It is simply DEFECTIVE. 
But @mananth does not change it just during several ( five or seven or even more ) years.
My impression of his writing is that he does not read what his code produces, because it is not interesting to him.


To me, it is monstrous style posting to the forum.