To calculate the charter school system payment for a charter school, the superintendent shall:

(1) Calculate the total amount of replacement system and depreciation system payments for the prior school year for the district in which the charter school is located.

(2) Calculate the combined student count for the prior year as defined in chapter 392-141 WAC for the district in which the charter school is located.

(3) Divide the amount in subsection (1) of this section by the number in subsection (2) of this section.

(4) Multiply the amount in subsection (3) of this section by the charter school's current year combined student count.