There are 850 books in the school library, 283 books have been borrowed, and 158 books have been returned. How many books are there in the library now?
学校图书馆共有850本图书，借出去了283本，又还回来了158本，现在图书馆里有多少本图书？
<gadget id="calculator">850 - 283</gadget>
<output>567</output>

<gadget id="calculator">567 + 158</gadget>
<output>725</output>

<result>725</result>