Question 770517
Analyzing in general:  w = wind speed; r = speed of plane in no wind. f = distance gone with the wind; b = distance gone against the wind; h = total time in hours flown.  Assume time values are unknown but h IS known.  Also assume w wind speed is unknown.


WAY________RATE_______________TIME____________DISTANCE
WITH_______r+w________________(__)____________f
AGAINST____r-w________________(__)____________b
Total___________________________h


Using r*t=d we find that any t=d/r.
r is rate, t is time, d is distance.


WAY________RATE_______________TIME____________DISTANCE
WITH_______r+w________________({{{f/(r+w)}}})____________f
AGAINST____r-w________________({{{b/(r-w)}}})____________b
Total___________________________h


Form the time equation, {{{highlight(f/(r+w)+b/(r-w)=h)}}} and solve for w, the wind speed, here assumed the unknown variable.  Note, the simplest common denominator for handling arithmetic steps is {{{(r+w)(r-w)}}}.