The library has a total of 650 books, among which popular science books account for (2/5) of all books, and story books account for (7/13) of the popular science books. How many story books are there?
图书馆共有图书650本，其中科普读物占全部图书的(2/5)，故事书占科普读物的(7/13)，故事书有多少本？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">7 / 13</gadget>
<output>7/13 = around 0.538462</output>

<gadget id="calculator">650 * (2/5) * (7/13)</gadget>
<output>140</output>

<result>140</result>