Section 16E. A regional school district shall be considered a district for purposes of conducting periodic audits under sections 35, 38, 39, 40, 41 and 42 of chapter 44. Upon the completion of each audit, a copy shall be sent to the chief executive officer and the school committee of each city or town that is a member of the district. The cost of each audit shall be apportioned among the several cities and towns that are members of the district in the same manner as the annual expenses of the district.