The ratio of speed of a train and a car is 9 ∶ 5. If the train of length 900 m long crosses a pole in 20 sec, then find the time in which the car is crosses by another train of length 840 m and speed 65 m/sec travelling in the same direction.
1
24 seconds
2
21 seconds
3
20 seconds
4
28 seconds
5
None of these