If you use a batch of paper to bind exercise books of the same size, if each book has 30 pages, you can bind 120 books; now you have bound 100 books with this batch of paper, how many pages should be bound in each book? (answer with ratio)
用一批纸装订同样大小的练习本，如果每本30页，可以装订120本；现用这批纸装订了100本，每本应装订多少页？(用比例解答)
<gadget id="calculator">120 * 30</gadget>
<output>3_600</output>

<gadget id="calculator">3_600 / 100</gadget>
<output>36</output>

<result>36</result>