There are 980 story books in the library, 460 were lent out today, and 150 were returned. How many story books are there in the library now?
图书室有故事书980本，今天借出460本，还回150本，现在图书室里有故事书多少本？
<gadget id="calculator">980 - 460</gadget>
<output>520</output>

<gadget id="calculator">520 + 150</gadget>
<output>670</output>

<result>670</result>