One person can do a certain job in six days, a second person can do the same job in two days, and a third person can do this job in three days. how many days will they take to do the job together?

First find their rates ...

1/6, 1/2, and 1/3 now combined they will perform the job in one day if:

t/6+t/2+t/3=1 make all have a common denominator

t/6+3t/6+2t/6=6/6 which is equal to:

6t=6 so

t=1

So if they all work together they will complete the job in one day.