Depreciation

Can anybody solve the below question and fully explain all procedures that lead to the final answer.

The plant and machinery account (at cost) of a business for the year ended 31 December 2008 was as follows:

Plant and machinery -Cost
]
2008 $ 2008 $
1 Jan Balance 240000 31 March Transfer disposal
account 60000
30 June Cash – Purchase
of plant 160000 31 Dec Balance 340,000
400000 400000

The company’s policy is to charge depreciation at 20% per year on the straight line basis ,
with proportionate depreciation in the years of purchase and disposal

What should be the depreciation charge for the year ended 31 December 2008?