The school library bought back 240 science and technology books, and the number of story books bought back was three times the number of science and technology books. How many story books were bought back?
学校图书室买回科技书240本，买回的故事书是科技书本数的3倍，买回的故事书有多少本？
<gadget id="calculator">240 * 3</gadget>
<output>720</output>

<result>720</result>