Answer:
It would take 1.5 hours for all three to finish the work if they worked together.
Explanation:
Elon and Jeff can complete the work in 3 hours.
Jeff and Bruce can complete the work in 6 hours.
Elon and Bruce can complete the work in 4 hours.
3 + 6 + 4 = 13
13 / 3 = 4.33
4.33 / 3 = 1.44