OP NOTES, Chapter 9 NCA, Example 2 – Revaluation decrease

Hello,
Not clear on the double entry for the reval. decrease.
Is it: CR asset 4250, DR: Equity Reval Reserves 3850 DR P&L Impairemnt Lesses: 400?
In the answer it is SOCI Impairemnt 400 and Impairemnt 3850. How then we Reverse balance on revaluation Revserve of 3850? Is this amount recognized in OCI and then DR to reserves?
Thank you:)

PS. I belive there is error in Chapter on Consolidated Statemnt of Cash flows, answer eg 4, Cash generated from operations does not sum up to 501 but 447.