Here's the question you clicked on:
yrelhan4
A train is moving with uniform velocity on a straight track. A boy moving at 4 km/h due east observes that the train is moving due north. Another boy moving at 1 km/h due south claims that the train is moving towards north-east. What is the speed of the train in ground frame ?
try to write expressions of relative velocities
done that. the question does not give me v of boys realtive to train. so how to go about it after that?