bpp book activity 3

On 1 December 20X0, Trail acquired 80% of the Dial’s 600 million $1 shares for a cash consideration of $800 million. At acquisition, the fair value of the non-controlling interest in Dial was $190 million. Trail wishes to measure the non-controlling interest at fair value at the date of acquisition. On 1 December 20X0, the retained earnings of Dial were $300 million and other components of equity were $20 million. The fair value of Dial’s net assets was equivalent to their book value.
On 30 November 20X1, Trail sold a 5% shareholding in Dial for $60 million. At 30 November 20X1, Dial had retained earnings of $450 million and other components of equity of $30 million.

) Non-controlling interest
$m
NCI at acquisition 190
NCI share of post-acquisition retained earnings to disposal
(20% ? [450 – 300]) 30
NCI share of post-acquisition other components of equity to disposal
(20% ? [30 – 10]) 4
NCI at date of disposal 224
Increase in NCI on date of disposal (224 ? 5%/20%) 56
NCI at year end 280

could you please explain why the NCI share of post- acquisition other components of equity to disposal has (30-10)*20% rather the 30-20