Question 839065
The cruising speed of an airplane is 320 miles per hours.
 With the wind the airplane can cover a certain distance in 6 hours, but against the wind it can cover only 7/8 of that distance in 6 hours.
 Find the velocity of the wind.
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Let's do it this way. 
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Let w = the velocity of the wind
then
Original distance = 6(320+w)
Against distance = 6(320-w)
the equation
6(320-w) = {{{7/8}}}*6(320+w)
divide both sides by 6
(320-w) = {{{7/8}}}*(320+w)
multiply both sides by 8
8(320-w) = 7(320+w)
2560 - 8w = 2240 + 7w
2560 - 2240 = 7w + 8W
320 = 15w
 w = 320/15
 w = 21{{{1/3}}} mph, rate of the wind
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You can check this on a calc
6(320+21.33) * {{{7/8}}}
see if it equals
6(320-21.333)