SOLUTION: A plane flies 400 miles with the wind and 320 miles against the wind in the same length of time. If the speed of the wind is 25 mph, what is the speed of the plane in still air?

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Question 116160This question is from textbook
: A plane flies 400 miles with the wind and 320 miles against the wind in the same length of time. If the speed of the wind is 25 mph, what is the speed of the plane in still air? This question is from textbook

Answer by checkley71(8403) About Me  (Show Source):
You can put this solution on YOUR website!
DISTANCE=RATE*TIME.
OR T=DISTANCE/RATE.
BECAUSE THE TIMES ARE THE SAME WE HAVE THE FOLLOWING EQUATION:
400/(R+25)=320/(R-25) CROSS MULTIPLY.
400(R-25)=320(R+25)
400R-10,000=320R+8000
400R-320R=800+18,000
80R=18000
R=18,000/80
R=225 MPH FOR THE SPEED OF THE PLANE.
PROOF
400/(225+25)=320/(225-25)
400/250=320/(200)
1.6=1.6