Question 372451
one clerk 35 minutes
other clerk 40 minutes
..
first clerk 1/35 of the job in 1 minute
second clerk 1/40 of the job in 1 minute
..
together they do 1/35   + 1/40 of the job in 1 minute
=(40+35)/40*35
=75/1400
=3/56 of the job in 1 minute
so they will take 56/3 = 18.66 hours together.
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m.ananth@hotmail.ca