Numbers 3:23

3:23 The families of the Gershonites were to camp behind the tabernacle toward the west.

Numbers 4:24

4:24 This is the service of the families of Gershonites, as they serve ¹  and carry it.

[4:24]  ¹ tn The two forms are the infinitive construct and then the noun: “to serve and for the burden.” They are to serve and they are to take the responsibility. The infinitive is explaining the verb.