Step disposal – control to control

Good day dear tutor,

I wanted to ask about one thing – you recommend to read ACCA article Business combinations – IFRS 3 (revised)

There is an example 5 about step disposal when no control is lost and we should record the increase in NCI.

EXAMPLE 5
Parent’s initial stake: 70%,Initial total net assets = 480m, Initial FV of NCI = 210m, full goodwill method is used for all acquisitions

Parent disposes of a 10% interest to the NCIs in sub on 31 December 2008 for a cash consideration of $65m. The carrying amount of the net assets of sub is $535m at 31 December 2008.

In the solution given (in the article) to calculate the decrease of NCI the goodwill of 90 is considered, which is similar to example 3 in the notes and lecture.
Transfer to NCI (10% x (535 net assets + 90 goodwill)) (62.5)

The increase to NCI, which I calculated, was 75.5 (being the NCI at acquistion 210 + NCI share of post acq reserves 16.5 and the ratio %sold to NCI before disposal 10%/30%). This is what was done in the OpenTution lecture for example 5 Reilly.

Both questions use full goodwill method but extract the NCI figure differently, so could you please explain which method I should follow to calculate the NCI and thus the difference to reserves?

Thanks a million!