<PRE><B>Question 931758</B>
x = train speed
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distance train traveled when car departed:
s = d/t
d = st
d = x7
d = 7x
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speed of car relative to train:
87 - x
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time elapsed from car departure to catching train:
t = d/s
7x / (87 - x) = 8
7x = 8(87 - x)
7x = 8*87 - 8x
7x + 8x = 8*87
15x = 8*87
x = 8*87/15
x = train speed = 46.4 mph
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