SOLUTION: A plane flies 420 miles with the wind and 350 miles against the wind in the same length of time. If the speed of the wind is 15mph, find the speed of the plane in still air.

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Question 1052252: A plane flies 420 miles with the wind and 350 miles against the wind in the same length of time. If the speed of the wind is 15mph, find the speed of the plane in still air.
Found 2 solutions by josgarithmetic, MathTherapy:
Answer by josgarithmetic(39615) About Me  (Show Source):
You can put this solution on YOUR website!
RT=D Constant Travel Rate Rule 
                  SPEED           TIME          DISTANCE
WITHWIND          r+15             t             420
AGAINSTWND        r-15             t             350

Remind yourself what the description said about the time quantities, and notice both are assigned as t.



continuing from the table,

420%2F%28r%2B15%29=350%2F%28r-15%29

6%2F%28r%2B15%29=5%2F%28r-15%29

6%28r-15%29=5%28r%2B15%29

6r-6%2A15=5r%2B5%2A15

r=5%2A15%2B6%2A15

r=11%2A15

highlight%28r=161%29--------speed of plane in still air.

Answer by MathTherapy(10551) About Me  (Show Source):
You can put this solution on YOUR website!

A plane flies 420 miles with the wind and 350 miles against the wind in the same length of time. If the speed of the wind is 15mph, find the speed of the plane in still air.
Speed of plane in still air: highlight_green%28matrix%281%2C2%2C+165%2C+mph%29%29