Let the two trains meet at D km from Mumbai. Then,
3:45 pm + D/50 = 2 : 35 pm + 510 - D/60
⇒ (3:45 pm - 2:35 pm) + (D/50 + D/ 60) = 510/60
⇒ (11/6 h) + D{( 50 + 60 / 50 x 60)} = 17/2
⇒ D(110/3000) = 17/2 - 7/6
⇒ D(110/3000) = (51 - 7)/6 = 44/6
∴ D = (44/6) x (3000/110) = 200 km