Answer:
200 KM/H
Explanation:
A plane has a speed of 840 km/h in still air. It can travel 3120 km with the wind in the same time it would take to travel 1920 km against the wind. Find the speed of the wind.
let x=speed of wind
(840+x)=speed of plane with wind
(840-x)=speed of plane against wind
Travel time = distance/speed (same with and against the wind)
3120/(840+x)=1920/(840-x)
cross-multiply
3120*840-3120x=1920*840+1920x
3120*840-1920*840=1920x+3120x
5040x=1008000
x=200 km/hr
answer
Speed of wind=200 km/hr