Question 631198
Trains are moving in same direction
so effective speed = 80-30 = 50 km/h

Time taken to cross the man in slower train = 24 seconds= 24/3600 hours

The length of the faster train is the distance traveled.
let it be D
d = speed * time
d= 50 *24/3600 
d= 24/72
d= 1/3 km
= 333 meters  ( rounded off)