Sheila operates a photocopying shop in Yau Ma Tei. In January 2021, her total sales were $150,000. She prepared a simple Income and Expense account for the month as follow: Revenue $150,000 Expense Cost of paper and printing powder $60,000 Salary $12,000 Depreciation $20,000 Profit $58,000 Sheila explained that the paper and printing powder used in January was purchased in December 2020 for an amount of $60,000. She paid a monthly salary to her shop assistant Paul $12,000 per month, while Sheila herself received nothing. She promised Paul that by the end of 2021, he will be paid a guaranteed bonus equal to 10% of his total salary received in 2021. Sheila bought the photocopying machines ($300,000) and renovated the shop ($180,000). She expected the machines as well as the decoration to last 24 months. By using the 'straight line method', she evenly spread this cost over 24 months to arrive at the depreciation cost for January. Based on your understanding of economics, comment on Sheila's treatment of the cost of operating the business in January 2021.