need help please.

XYZ Ltd has a balance day of 31 December. On 1 January 2XX3, it had an opening inventory balance of $12,000. XYZ Ltd purchased $23,000 worth of goods for resale. On 31 December 2XX3, the closing inventory balance was $10,000. During the year, XYZ Ltd had sales of $40,000. What is the Cost of Goods Sold for XYZ Ltd for the period ending 31 December 2XX3?

how can I calculate the COGS?