The school has 684 story books and 147 science and technology books. Students borrowed 344 of these two kinds of books. How many books are left?
学校有故事书684本，科技术书147本，两种书学生共借走344本，还剩下多少本？
<gadget id="calculator">147 - 344</gadget>
<output>-197</output>

<gadget id="calculator">684 + (-197)</gadget>
<output>487</output>

<result>487</result>