Depreciation for Revaluated Non- current asset

Follow your lectures, i understand that when the asset is revaluated, the depreciation for the past year will not be recalculated, and the revaluation surplus is the exceed of revaluated value and carrying value (initial cost – accumulated depreciation), the new annual depreciation will be calculated by getting current cost divided by remaining useful life (not whole useful life)

However, follow Activity 3 of BPP Learning Material (Chapter 3- page 44&45), the answer for question 2 & 4 & 5 show that carrying amount of PPE at 30 Sep 20X8 was recalculated by getting current cost minus re-calculated depreciation which is based on current cost and whole useful life. It also means the annual depreciation will be calculated by getting current cost divided by whole useful life.

Can you help to explain why it was calculated in 2 different ways?