This question seems to have been asked not long ago. . The key to this problem is that different kinds of figures can't be added up casually. . 490+490=980 Two 490 s in this formula are liabilities, and 980 means that it always owes so much money. So what's the money for? Obviously, 970 of them are used to buy shoes. . I still have the remaining ten dollars, which means that this 10 yuan was originally included in 980. How do you add them up? Then 990 means nothing.

Hope to adopt. .