Maria, an experienced shipping clerk, can fill a certain order in 14 hours. Jim, a new clerk, needs 17 hours to do the same job. Working together, how long will it take them to fill the order?

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Answer 1 · 2018-05-21T15:43:00

About #7 2/3# hours or #7# hours and #40# minutes

Consider how much of the task each would complete in one hour:

Maria will complete #1/14# of the order in one hour.
Jim will complete #1/17# of the order in one hour.

So if they work together, then after one hour:

#1/14+1/17# of the order will have been completed.

#= (17+14)/(14xx17)#

#=31/238#

To complete the whole task, a whole, or #1 or 238/238# will take:

#238/238 div 31/238#

#= 1 xx 238/31#

#=7 21/31# hours

#= 7 # hours and # 40.6# minutes