How do you workout the unrealised profit on inter-company sales?

The Davidson Group consists of two companies, Davidson Ltd and Stevenson Ltd. Their financial statements for the year to 31 December 2019 are as follows: Statements of profit or loss for the year ended 31 December 2019 Davidson Ltd Stevenson Ltd '000 '000 Revenue 42,000 12,000 Cost of sales 24,000 Gross profit 1 1 8,000 4,800 Distribution costs 950 1,000 Administrative expenses 850 550 Profit for the year 16,200 3,250 Dividend receivable 1,440 Proposed dividend 12.000 1,800 Retained profit for the year 5.640 1.450 Stevenson Ltd '000 6,900 6,900 Statements of financial position as at 31 December 2019 Davidson Ltd '000 Assets Non-current assets Plant and machinery 34,200 Investment in Stevenson Ltd 9,600 43,800 Current assets Inventories 14,400 Amount due from Stevenson Ltd 900 Trade receivables 8,700 Dividend receivable 1,350 Cash at bank 1.890 27,240 Total assets 71,040 6,000 3,300 600 9.900 16,800 Equity and liabilities Equity Ordinary share capital Retained earnings 24,000 25,200 49,200 3,000 5,350 8,350 T. Liabilities Current liabilities Trade payables ount due to Davidson Ltd Dividend payable Other payables 7,440 - 12,000 2,400 71.040 3,600 900 1,800 2,150 16.800 2. Davidson sells goods to Stevenson at cost plus 50%. During the year to 31 December 2019 intergroup sales totaled 1,980,000 of which 470,000 was still owing to Davidson on 31 December 2019. Stevenson's inventory on 31 December 2019 included goods purchased from Davidson for 1,440,000