Question 1063308
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Flying against the wind, a jet travels 3780 mi in 7 hours. Flying with the wind, the same jet travels 9000 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>
u + v = {{{9000/9}}}   (speed WITH the wind)
u - v = {{{3780/7}}}   (speed AGAINST the wind)


OR (which is the same)

u + v = 1000,  (1)
u - v =  540.  (2)


Add the equations (1) and (2) (both sides). You will get

2u = 1540  ---->  u = {{{1540/2}}} = 770 mph. It is the speed of the plane at NO WIND.

Then from (1) v = 1000 - 770 = 230 mph.  It is the speed of wind.
</pre>

By the way, speed of wind of 230 mph is more than VERY STRONG hurricane condition.


But what to the person who invented this text, to it?