30 miles per hour is the speed of the train.
Logic: use below line as clue
each boy managed to escape the train at the exact instant in which the train would have hit and killed him
let A is running toward the train and B is moving in opposite direction.
So the distance which A has to cover=1-2/3=1/3
the distance which B has to cover=2/3
and speed of A and B is same hence A and B will cover the same distance 1/3,
A just escaped when train is at the entrance of the tunnel hence remaining distance for B is 2/3-1/3=1/3
Now B will cover 1/3 and train will cover 2/3 for the clue line to be true
hence train will run 3 times faster then B