N.C. Gen. Stat. § 115C-430
If there is more than one local school administrative unit in a county, all appropriations by the county to the local current expense funds of the units, except appropriations funded by supplemental taxes levied less than countywide pursuant to a local act of G.S. 115C-501 to 115C-511, must be apportioned according to the membership of each unit. County appropriations are properly apportioned when the dollar amount obtained by dividing the amount so appropriated to each unit by the total membership of the unit is the same for each unit. The total membership of the local school administrative unit is the unit's average daily membership for the budget year to be determined by and certified to the unit and the board of county commissioners by the State Board of Education.
N.C. Gen. Stat. § 115C-430