Gain or loss on disposal

Kutchen had purchased an 80% interest in Niche for $40 million on 1 January 20X6 when the
fair value of the identifiable net assets was $44 million. The partial goodwill method had been
used to calculate goodwill and an impairment of $2 million had arisen in the year ended 31
December 20X6. The holding in Niche was sold for $50 million on 31 December 20X6. The
carrying amount of Niche’s identifiable net assets other than goodwill was $60 million at the
date of sale. Kutchen had carried the investment in Niche at cost. The finance director
calculated that a gain arose of $2 million on the sale of Niche in the group financial
statements being the sale proceeds of $50 million less $48 million being their share of the
identifiable net assets at the date of sale (80% of $60 million). This was credited to retained earnings

In this scenario while calculating gain or loss on disposal they are not considering the value of NCI at disposal.could you please explain why?