(a) Multiplies the one-way commercial costs for all schools by four to identify the total commercial costs for all schools;

(b) Subtracts the commercial cost total from the appropriated transportation funds and allocates the balance of the transportation funds to each school with a per-mile rate;

(c) Divides the balance of funds by the sum of the annual day miles and the annual residential miles to identify a per-mile rate;

(d) For day transportation, multiplies the per-mile rate times the annual day miles for each school; and

(e) For residential transportation, multiplies the per mile rate times the annual transportation miles for each school.