SOLUTION: An express train takes 1.5 hour less than a passenger train for distance of 180 km. the speed of passenger train is 20 km/h less than express train. find speed of both the trains.

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Question 930283: An express train takes 1.5 hour less than a passenger train for distance of 180 km. the speed of passenger train is 20 km/h less than express train. find speed of both the trains.
Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!

s (mi/hr) the speed of the slower train
180mi%2Fs++-+180%2F%28s%2B20%29+=+1.5hr
180(s+20) - 180s = 1.5s(s+20)
%283%2F2%29s%5E2+%2B+30s+-+3600+=+0 |Multiplying thru by 2/3 so as all denominators = 1
s^2 + 20s - 2400 = 0 (tossing out negative solution for unit measure)
(s+60)(s-40)= 0
s = 40mph, the speed of the slower train. Faster train 60mph
And...checking
180mi/40mph - 180mi/60mph = 4.5hr - 3hr = 1.5hr