Question 1196115
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Flying against the wind, a jet travels 3600 miles in 4 hours. 
Flying with the wind, the same jet travels 7980 miles in 7 hours. 
What is the rate of the jet in still air and what is the rate of the wind?
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<pre>
Flying against the wind, the jet' speed relative the earth surface is  

    {{{3600/4}}} = 900 miles per hour.


Flying with    the wind, the jet' speed relative the earth surface is  

    {{{7980/7}}} = 1140 miles per hour.


Let "u" be the jet' speed in still air and let "v" be the rate of the wind.

Then we have this system of equations

    u + v = 1140    (1)

    u - v =  900    (2)


Find "u" by adding equations (1) and (2)

    2u    = 1140+900 = 2040,  u = 2040/2 = 1020.


Find "v" by subtracting equation (2) from equation (1)

    v - (-v) = 1140-900,  2v = 240,  v = 240/2 = 120.


<U>ANSWER</U>.  The jet' speed in still air is 1020 miles per hour.

         The rate of the wind is 120 miles per hour.
</pre>

Solved.


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It is a typical "tailwind and headwind" word problem.


See the lessons 

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=http://www.algebra.com/algebra/homework/word/travel/Wind-and-Current-problems.lesson>Wind and Current problems</A> 

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=http://www.algebra.com/algebra/homework/word/travel/Wind-and-Current-problems-solvable-by-quadratic-equations.lesson>Wind and Current problems solvable by quadratic equations</A> 

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/word/travel/Selected-problems-from-the-archive-on-a-plane-flying-with-and-against-the-wind.lesson>Selected problems from the archive on a plane flying with and against the wind</A> 

in this site, where you will find other similar solved problems with detailed explanations.



Also, &nbsp;you have this free of charge online textbook in ALGEBRA-I in this site

&nbsp;&nbsp;&nbsp;&nbsp;<A HREF=https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson>ALGEBRA-I - YOUR ONLINE TEXTBOOK</A>.


The referred lessons are the part of this textbook under the section "<U>Word problems</U>", &nbsp;the topic "<U>Travel and Distance problems</U>".



Save the link to this online textbook together with its description


Free of charge online textbook in ALGEBRA-I
https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson


to your archive and use it when it is needed.