@Tuan: Yes, the right answer is: Net asset = 13,200+7,500-2,250 = 18,450
But I think we should minus 7,500 because the good worths 7,500 has sold, and we have not received money. It means Asset decreases 7,500, and we also minus 7,500 in Capital to ensure the equility of accounting equation. ???
When Nancy purchase new equipment, her Cash (Asset) decreases 1,200 while her non – current Asset increases 1,200. So this transaction seems to have no effect to accounting equation.