Question

A plane flies 440 miles with wind, and 340 miles against wind in same time. If speed of wind is 25 mph, find speed in still air? Help please?

Answer 1

v = s/t

now, t is equal for both cases so we write these 2 equations:
440/(Vp+Vw) = t

and 

340/(Vp-Vw) = t
Now again, since t is equal for both cases we can make these 2 equations equal to eachother.
440/(Vp+25) = 340/(Vp-25)
(Vp - 25)*44=34*(Vp+25)
44Vp - 1100 = 34Vp + 850
10Vp = 1950
Vp = 195

Answer is 195mph