your statement about the question here is wrong, you should look up the original question, i still remembered the statement should be like the following:
after sold 10000 hardbook, the sellor bought another 30000 books including hardbooks and softbooks to sell, there is number raio of hardbook to softbook, also you can find the price raio of the two kinds of books,
just go to find the correct statement of question, you will understand the answer easily, the answer is correct here作者: tongxun 时间: 2002-10-21 16:30