Adjustment on the cost of non current asset

as at 31 December 20X4: Plant and equipment 21,000 Accumulated 9,000 Carrying amount 12,000 (b) The balance of the account is the proceeds of sale of some plant on 1 January 20X4 with a carrying amount at the date of sale of $700,000 and which had originally cost $1,400,000. No other accounting entries have yet been made for the disposal apart from the cash book entry for the receipt of the proceeds. Depreciation on plant has been charged at 25% (straight line basis) in preparing the draft statement of financial position without allowing for the sale. The depreciation for the year relating to the plant sold should be adjusted for in full. Solution: Workings 1 Plant and equipment $'000 Disposal – Cost 1,400 – Depreciation (700) – Carrying amount 700 Proceeds (part (a)) (600) Loss on sale 100 Cost adjustment 21,000 – 1,400 = 19,600 Accumulated depreciation adjustment (9,000 – 700 – (1,400 ? 25%)) = 7,950 Retained earnings $'000 Per draft 12,400 Irrecoverable debts (200) Inventory write down (500 – 360) (140) Loss on disposal of plant (W1) (100) Depreciation adjustment (1,400 ? 25%) (W1) 350 12,310. Please I don't understand the adjustments on the cost of plant and equipment ?