SOLUTION: A plane flies 435 miles with the wind and 345 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.

Question 428014: A plane flies 435 miles with the wind and 345 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.
Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
let speed in still air be x mph
wind speed 10 mph
..
against wind x - 10 mph
with wind x + 10 mph

Distance against wind 345
Distance with tail wind 435
Time = same
345 /(x- 3 )= 435 /(x+ 3 )
345 *(x+ 3 )= 435 *(x- 3 )
345 x + 1035 = 435 x -1305
435 x -345 x = 1305 + 1035
90 x = 2340
/ 90
x= 26 mph

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