Use a batch of paper to bind exercise books, each book has 20 pages, and 300 books can be bound. If each book is bound with 10 more pages, how many books can be bound in this way? (Solve using ratio method)
用一批纸装订练习本，每本20页，可以装订300本，若每本多装订10页，这样可装订多少本？(用比例方法解答)
<gadget id="calculator">20 * 300</gadget>
<output>6_000</output>

<gadget id="calculator">20 + 10</gadget>
<output>30</output>

<gadget id="calculator">6_000 / 30</gadget>
<output>200</output>

<result>200</result>