A 280metre long train moving with an avg speed of 108 km/hr crosses a platform in 12 sec. A man crosses the same platform in 10sec.what is the speed of the man in metre/sec?

8m/s

The speed of the train in m/s is 108*5/18 = 30 m/s
As it took the train 12 seconds to cross the platform, the total distance covered is 12*30 = 360 m/s
The length of the train is 280 m, hence the length of the platform is 100 m

If a man crosses the platform in 10 seconds, his speed is 100/10 = 10 m/s