Binding a batch of the same exercise books, originally planned to have 16 pages per book, can be bound to 250 books, if it is to be bound into 200 books, how many pages should be packed in each book? (Solve with ratio)
装订一批同样的练习本，原计划每本装16页，可以装订250本，如果要装订成200本，每本应装多少页？(用比例解)
<gadget id="calculator">250 * 16</gadget>
<output>4_000</output>

<gadget id="calculator">4_000 / 200</gadget>
<output>20</output>

<result>20</result>