(1) In assessing a consolidated tax effect shall be given to any partial or total exemption from any single tax comprised therein.
(2) Such effect shall be given —
(a) in the case of partial exemption, by means of the deduction from the total amount of the consolidated tax which would otherwise be leviable or assessable in respect of any buildings, or lands or both to which the exemption applies, of a proportionate part, corresponding to the exemption, of the amount which might otherwise have been assessed on account of the single tax ; and
(b) in the case of a total exemption, by means of the deduction from such total amount of the whole amount assessed, on account of the single tax.