SOLUTION: An airplane flies 840 mi in 3 hours with a tail wind. The return trip at the same airspeed takes 3.5 hours. Find the wind speed and the airspeed.

Algebra ->  Algebra  -> College  -> Linear Algebra -> SOLUTION: An airplane flies 840 mi in 3 hours with a tail wind. The return trip at the same airspeed takes 3.5 hours. Find the wind speed and the airspeed.      Log On


   

Question 318962: An airplane flies 840 mi in 3 hours with a tail wind. The return trip at the same airspeed takes 3.5 hours. Find the wind speed and the airspeed.
Answer by Fombitz(13828) About Me  (Show Source):
You can put this solution on YOUR website!
Rate*Time=Distance
.
.
.
Let P be the plane speed, W the wind speed.
.
.
.
%28P%2BW%293=840<--- with the wind
1.P%2BW=280mph
.
.
.
%28P-W%293.5=840<--- against the wind
2.P-W=240mph
.
.
.
Add eq. 1 and eq. 2 to eliminate W,
P%2BW%2BP-W=280%2B240
2P=520
highlight%28P=260%29
Then use either equation to solve for W,
260%2BW=280
highlight%28W=20%29