if you meant 3900 kilometer by '3900k'....
Originally Posted by Infiniti
Let the speed of the airplane as 'x km/hr'
Let the speed of the headwind as 'y km/hr'
Then the speed of the tailwind would be '2y km/hr'
Then you can get two simultaneous equations since 'distance = speed x time'
If you solve the equation, it'll be clear that
the speed of the airplane is 3600 km/hr
the speed of the headwind is 60 km/hr
and the speed of the tailwind is 120 km/hr.
So the answer for the problem (a) would be 60km/hr and 120km/hr
And the answer for the problem (b) would be 3600km/hr