If the company elects to have its portion of the paving done by the municipality, then, and before proceeding to apportion the cost of the improvement upon any lots or parcels of ground abutting on or adjacent to the highway, the board shall first deduct from the total of the improvement the amount that should be paid by such company; and after deducting the amount that is to be paid by such street or other railway company, the legislative body shall proceed to apportion two thirds (2/3) of the balance of the cost of such improvement upon the land abutting on and adjacent to such street, highway, avenue, or alley, as provided in this chapter.