NET

24 These were the descendants of Levi according to their families, that is, the leaders of families as counted and individually listed who carried out assigned tasks in the Lord’s temple and were twenty years old and up.

Darby

24 These were the sons of Levi according to their fathers' houses, the chief fathers, as they were reckoned, by number of names by their polls, who did the work of the service of the house of Jehovah, from twenty years old and upward.

KJV

24 These [were] the sons of Levi after the house of their fathers; [even] the chief of the fathers, as they were counted by number of names by their polls, that did the work for the service of the house of the LORD, from the age of twenty years and upward.