If Sam can do a job in 4 days, he can do 1/4 of the job in a day.

If Bob can do it in 6 days, he can do 1/6 of the job in a day.

If Tom can do it in 2 days, he can do 1/2 of the job in a day.

Together, they can do of the job in a day. If they can do of the job in a day, they can do the job in days.