The Commission shall study the preliminary plat and other materials for conformity thereof to the regulations set forth in this chapter. The Commission may confer with the subdivider on changes deemed advisable and the kind and extent of such improvements to be made by the subdivider. The Commission shall approve or reject such plat within 45 days after the date of submission thereof to the Commission. If the Commission does not act within 45 days, the preliminary plat shall be deemed to be approved; provided, however, the subdivider may agree to an extension of the time for a period not to exceed 60 days.