<PRE><B>Question 740638</B>
12 carpenters take 30 days to build a house
To build the house in 1/5 that time would take
5 times as many carpenters, so
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60 carpenters take 6 days to build a house
If they have 4 times as long to build the house, 
they can do it with 1/4 as many carpenters, so
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15 carpenters take 24 days to build a house
They started with 12 carpenters, so
they have to add 3 more to finish it in 24 days
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