Question 307823: A plane flies 1080 miles with the wind in 9hr. The return trip takes 12 hr. What speed of the wind and the speed of the plane in the air? Answer by mananth(16946) (Show Source):
You can put this solution on YOUR website! let the speed of wind be x
speed of plane be y
Speed of plane with wind = x+y mph
time taken by plane with wind = 1080 / x+y = 9 hours
1080= 9x+9y
Speed of plane against wind = y-x mph
time taken by plane against wind = 1080 / y-x = 12 hours
12y-12x = 1080
4(9x+9y)+3(12y-12x)= 4*1080+3*1080
36x+36y+36y-36x= 4320 +3160
72 y= 7480
y= 104 mph speed of plane
9x+9y= 1080
9x+9*104= 1080
9x= 1080-936
9x= 144
x=16 mph the speed of wind
