(a)"accumulated loss" means so much of loss of the amalgamating co-operative bank or the demerged co-operative bank, as the case may be, under the head "Profits and gains of business or profession" (not being a loss sustained in a speculation business) which such amalgamating co-operative bank or the demerged co-operative bank, would have been entitled to carry forward and set off under the provisions of section 72 as if the business reorganisation had not taken place;