The number of books stored on a bookshelf is between 30 and 100, among which (2/7) are comic books, (1/9) are story books, how many books can be stored on the bookshelf at most.
一个书架上存书的本数在30～100之间，其中(2/7)是连环画，(1/9)是故事书，书架上存书最多有多少本．
<gadget id="calculator">7 * 9</gadget>
<output>63</output>

<result>63</result>