A train, travelling at 30 kmph, completely crosses another train having 4/5th of its length and travelling in the opposite direction at 42 kmph, in 36 seconds. If it also passes a railway platform in 4 min. Then, what is the length of the platform?
1
1600 m
2
1540 m
3
1650 m
4
1750 m
5
None of these