Read the passage below and solve the questions based on it.
A jetfighter moving 3 km above the ground with a speed of 360 km/h tries to cross the border. A radar station notices it at distance of 6 km from the Jet. But it can fire anti-craft missile only when the plane enters in its border. The border is at a distance of km from radar station. (Assume that the fighter moves in a straight line in the same plane with the same speed)
If it fires the missile at the fighter as soon as it notices the jetfighter such that it will hit the fighter as soon as it enters in the borderline, then at what speed should the be missile fired?