Impairment of Goodwill proportionate Method

Hello, I was wondering if you could explain the following please. I have worked through the Illustration in Chapter 4 (Belfast/Dundalk example) I understand that the goodwill is grossed up to 35. Once the impairment is calculated (at 40m) we effectively remove the 7m that was used to gross up. Therefore the "real impairment loss" is calculated as 33m, 28m reduces goodwill to 0 with the remaining 5 allocated to s's net assets. I have read the example in the technical article: https://www.accaglobal.com/ie/en/student/exam-support-resources/professional-exams-study-resources/strategic-business-reporting/technical-articles/impairment-goodwill.html It appears to deal with the loss differently, if I am understanding correctly? Goodwill is grossed up from 300 to 500m. Impairment loss is then calculated as 50m. Based on the opentuition example I was going to the remove the 200m, though this would leave -150m? Instead, in the technical article the parent’s share of the goodwill impairment loss is recorded as 60% x $50 = $30. If we had applied this to the Belfast/Dundalk example, it would mean 40m*80% 32m. Is there a difference in method between the two articles? (or have I just totally confused myself :-))? Thank you for your time.