Petitions for the annexation of territory to, or detachment of territory from, a district shall be signed as follows:
(a) For a registered voter district, by any of the following:
(1) Not less than 25 percent of the registered voters within the affected territory.
(2) Not less than 25 percent of the number of landowners within the affected territory who also own not less than 25 percent of the assessed value of land within the territory.
(b) For a landowner-voter district, by not less than 25 percent of the number of landowners owning land within the affected territory who also own not less than 25 percent of the assessed value of land within the territory.