posted by Kiki .
a train left podunk and traveled west 70 km/h. two hours later, another train left podunk and traveled east at 90km/h. how many hours had the first train traveled when they were 1420 km apart?
After t hours since the second train left the station,
the first train went 70t + 140
the second train 90t
so solve 70t + 140 + 90t = 1420
(I got t=8, confirm this please)