Annual depreciation rate of double declining balance method =2/ 10=20%
Depreciation in the first year =30000×20%=6000
Depreciation in the second year =(30000-6000)×20%=4800.
Depreciation in the third year =(30000-6000-4800)×20%
And so on to the eighth year.
The remaining two years are averaged by net value-residual value.
12345 depreciation rates are10/(1+2+3+..10), 9/(1+2+3+..10) and 8.
Annual depreciation is 30000-3000× annual depreciation rate respectively.