reducing balance depreciation

Hi, I am a little bit confused on this question The plant and machinery at cost account of a business for the year ended 30 June 20X4 was as follows: PLANT AND MACHINERY – COST $ $ 20X3 20X3 1 Jul Balance 240,000 30 Sep Transfer disposal account 60,000 20X4 20X4 1 Jan Cash – purchase of plant 160,000 30 Jun Balance 340,000 400,000 400,000 The company's policy is to charge depreciation at 20% per year on the reducing balance basis, with proportionate depreciation in the years of purchase and disposal. What should be the depreciation charge for the year ended 30 June 20X4? The answer is $55,000 Workings 1 July 20X3 – 30 Sep 20X3 (3 months): P&M Cost = 240,000 Depreciation = 240,000*20%*3/12 = 12,000 1 Oct 20X3 – 31 Dec 20X3 (3 months): P&M Cost = 240,000-60,000 (disposed) = 180,000 Depreciation = 180,000*20%*3/12 = 9,000 1 Jan 20X4 – 30 June 20X4 (6 months): P&M Cost = 340,000 Depreciation = 340,000*20%*6/12 = 34,000 Total Depreciation Charge = 12,000+9,000+34,000 = 55,000 I d like to know that if we have to subtract 9000 depreciation charge from 340,000 P&M Cost before applying 20% depr.rate because of reducing balance method? Thanx in advance