A train crosses a bridge of length 150 m in 15 s and a man standing on it in 9 s. The train is travelling at a uniform speed. Length of the train is?

Let the length of the train be L m.
According to the question,
L/9 = Speed ...(i)
and (L + 150)/15 = Speed ..(ii)
from Eqs. (i) and (ii) we get
L/9 = (L + 150)/15
⇒ L/3 = (L + 150)/5
⇒ 5L = 3L + 450
⇒ L = 225 m