The school library bought back 300 science and technology books, which were story books (3/5). How many story books did the school buy back?
学校图书馆购回300本科技书，是故事书的(3/5)．学校购回故事书多少本？
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">300 / (3/5)</gadget>
<output>500</output>

<result>500</result>