On $31$ December $2020$ Auto & More Co$.$ sold a car to a customer for $30,000$ cash. The invoice price includes after sale servicing for $12$ months which is estimated to cost Auto & More Co$.1,800$ to provide. Auto & More Co$.$ generates a gross profit margin of $25\%$ on after sales servicing.According to IAS $18-$ 'Revenue, what items should be included in the income statement for $2020$ and in the balance sheet at $31$ December $2020?$