A train leave a station traveling north at 50km/hr. 3 hours later a second train leaves on parrallel tracks travels north at 90km/hr. how far from the station will they meet?

- - The first train leaves the station, going 50km/hr.

- - 3 hours later, when the 2nd train starts out, the first train

has covered (3 x50) = 150 km.

- - When they're both moving, the 2nd train gains (90 - 50) = 40km

on the first train each hour.

- - The second train gains the 150km that he was behind, and overtakes

the first train, in (150 / 40) = 3.75 hours.

- - In that 3.75 hours, the second train has covered (3.75 x 90) = 337.5km,

and that's the distance from the station to the place where they 'meet'.