<PRE><B>Question 526667</B>
a passenger train leaves the station 3 hours after a freight train left the same station. the freight train travels 30 mph slower than the passenger train. Find the rate of each if the passenger train catches up with the freight train in 4 hours.
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let x=rate of speed of passenger train
x-30=rate of speed of freight train 
Distance=rate of speed*travel time (same for both trains)
travel time for freight train=3+4=7hrs
travel time for passenger train=4hrs (given)
7(x-30)=4x
7x-210=4x
3x=210
x=70
x-30=40
Ans:
rate of speed of passenger train=70 mph
rate of speed of freight train =40 mph</PRE>