Answer: speed of plane is 720 km/h
Speed of wind is 80km/h
Step-by-step explanation:
Let x represent the speed of the plane.
Let y represent the speed of the wind.
The plane flies from Atlanta to los Angeles and against the wind in 5hrs and the distance between Atlanta and los Angeles is 3200 km.
Since it flew against the wind, the speed would be x-y km/hour
Distance = speed × time. Therefore
3200 = 5(x - y )
3200 = 5x - 5y - - - - - - - - - 1
the return trip back to Atlanta with the wind only 4 hr. This means that the speed is x+y km/hour. Therefore
3200 = 4(x+y)
3200 = 4x + 4y - - - - - - - - 2
Multiplying equation 1 by 4 and equation 2 by 5, it becomes
12800 = 20x - 20y
16000 = 20x - 20y
Adding both equations, it becomes
28800 = 40x
x = 28800/40 = 720
Substituting x = 720 into 3200 = 5(x - y )
x - y = 3200/5 = 640
y = 720 - 640 = 80
