<PRE><B>Question 923904</B>
s = d/t
d = st
t = d/s
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distance between trains when 2nd train leaves station:
d = st
d = 40*3
d = 120 miles
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speed of 2nd train relative to 1st train:
s = 56 - 40
s = 16 mph
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time for trains to meet:
t = d/s
t = 120/16
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answer:
t = 7.5 hours
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