The members of the boards of township supervisors and the township clerks present at the meeting provided for in section 58-02-14 shall determine the amount due from the annexed territory to the township to which it has been annexed by taking into account the assets and liabilities of the township to which the new territory has been annexed and of the township or fraction of a township annexed thereto. Such amount must be determined by the relative valuation of the annexed territory and of the township to which the annexation has been made as shown by the last preceding assessment.