why is the revised selling price deducted from the cost price in the working? Could you simply explain and highlight the double entries please

Note 1: stock Selling price mark-up Cost price 2 tables Selling price mark-up Cost price revised selling price Stock at lower of cost or NRV SP-cost Balance sheet value \begin{tabular}{|rr|} \hline & % \\ \hline 325,000 & 130% \\ 75,000 & 30% \\ \hline 250,000 & 100% \\ \hline \end{tabular} \begin{tabular}{|rr|} \hline & % \\ \hline 41,600 & 130% \\ 9,600 & 30% \\ \hline 32,000 & 100% \\ \hline 10,000 & \\ \hline \end{tabular} 250,00022,000228,000 \begin{tabular}{|l|r|r|} \hline & Dr & Cr \\ \hline & & \\ \hline Land, at valuation & 240,000 & \\ \hline Buildings: cost & 500,000 & \\ \hline Buildings: accumulated depreciation at 1 January 2019 & & 180,000 \\ \hline Equipment: cost & 392,000 & \\ \hline Equipment: accumulated depreciation at 1 January 2019 & & 152,000 \\ \hline Vehicles: cost & 568,000 & \\ \hline Vehicles: accumulated depreciation at 1 January 2019 & & 264,000 \\ \hline Inventory at 1 January 2019 & 214,000 & \\ \hline Trade receivables & 366,000 & \\ \hline Provision for doubtful debts at 1 January 2019 & & 16,000 \\ \hline Prepayment at 1 January 2019 & 12,000 & \\ \hline Accrual at 1 January 2019 & & 18,000 \\ \hline Cash & 408,000 & \\ \hline Trade payables & & 248,000 \\ \hline Share capital: ordinary 50p shares & & 50,000 \\ \hline Share premium & & 350,000 \\ \hline Retained earnings & & 606,000 \\ \hline Sales & & 2,924,000 \\ \hline Purchases & 976,000 & \\ \hline Wages and salaries & 540,000 & \\ \hline Distribution costs & 200,000 & \\ \hline Other administrative expenses & 360,000 & \\ \hline Corporation tax & 12,000 & \\ \hline Disposal account & 4,828,000 & 4,828,000 \\ \hline Dividend paid & & \\ \hline & & 20,000 \\ \hline \end{tabular} i. Ferguson prices its furniture using a normal 30% mark-up policy. A stock count carried out at 31 December 2019 valued stock at a selling price of 325,000. This included two items at a normal selling price of 20,800 each, which the directors have decided should be reduced in price to 5,000 each