There are less than 70 books on a shelf, among which literary books account for (3/7), scientific and technological books account for (2/9), how many other books are there?
一个书架上不到70本书，其中文艺书占(3/7)，科技书占(2/9)，其它书有多少本．
<gadget id="calculator">7 * 9</gadget>
<output>63</output>

<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">63 * (3/7)</gadget>
<output>27</output>

<gadget id="calculator">2 / 9</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">63 * (2/9)</gadget>
<output>14</output>

<gadget id="calculator">63 - 27 - 14</gadget>
<output>22</output>

<result>22</result>