A train moving with uniform speed crosses a pole in 2

A train moving with uniform speed crosses a pole in 2 s and a 250 m long bridge in 7 s. Find the length of the train?

Let length of the train be L m.
According to the question,
L/2 = (L + 250)/7
⇒ 7L = 2L + 500
⇒ 7L - 2L = 500
⇒ 5L = 500
∴ L = 500/5 = 100 m