Answers

2014-09-03T20:31:55+08:00
They clean the room for 7 hours
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2014-09-03T20:56:04+08:00
Jun can clean a room in 4hrs
thus
       in 1hr he can clean 1/4 part of a room
Ana can clean the same room in 3hrs
thus
       in  1 hr she can clean  1/3 part of a room
working together in 1 hr, they can clean  1/4 +1/3 = 7/12
part of a room
therefore time taken to clean the whole room = 12/7
   1 5/12 hrs



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