SOLUTION: "A plane flies 300 miles with a tail wind in 1 hour. It takes the same plane 2 hours to fly the 300 miles when flying against the wind. What is the plane's speed in still air?"

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Question 604449: "A plane flies 300 miles with a tail wind in 1 hour. It takes the same plane 2 hours to fly the 300 miles when flying against the wind. What is the plane's speed in still air?"
A) 75 MPH
B) 300 MPH
C) 225 MPH
D) 150 MPH

Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
x = speed of plane in still air (in mph)
w = wind speed (in mph)
The plane's speed with tail wind is x+w.
The plane's speed going against the wind is x-w
1(x+w)=300 <---> x+w=300
2(x-w)=300 <---> 2x-2w=300
We have a system of two equations and many ways to solve it.
We can multiply the first equation times 2 and add the second equation to get
2(x+w)+2x-2w=2(300)+300 ---> 2x+2w+2x-2w=600+300 ---> 4x=900 --> 4x/4=900/4 ---> x=225
The speed of the plane in still air is 225 mph