We need to calculate the depreciation rate for Diminishing-balance method:
Depreciation rate = 2 / Useful life
Depreciation rate = 2 / 20 = 0.10
Now, we can calculate the carrying amount and accumulated depreciation for December 2018:
Year 1:
Beginning Carrying Amount = $30,000,000
Depreciation Expense = $30,000,000 x 0.10 = $3,000,000
Accumulated Depreciation = $3,000,000
Year 2:
Beginning Carrying Amount = $27,000,000 ($30,000,000 - $3,000,000)
Depreciation Expense = $27,000,000 x 0.10 = $2,700,000
Accumulated Depreciation = $3,000,000 + $2,700,000 = $5,700,000
Year 3 (December 2018):
Beginning Carrying Amount = $24,300,000 ($27,000,000 - $2,700,000)
Depreciation Expense = $24,300,000 x 0.10 = $2,430,000
Accumulated Depreciation = $5,700,000 + $2,430,000 = $8,130,000
Therefore, the carrying amount for December 2018 is $24,300,000 and the accumulated depreciation is $8,130,000.