Question 380186
each rider speed = 10 mph
distance apart 20 mile
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so they meet midway that is 10 miles.
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to travel 10 miles the rider takes 10/10 = 1 hour.
They meet after 1 hour.
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speed of fly = 15 mph.
the fly keeps flying for one hour to and fro from the riders.
It flies for 1 hour : 
so distance it flies = 15 miles.
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m.ananth@hotmail.ca