There are 45 elementary school students in a class, and the statistics of borrowing extracurricular books are: all students in the class borrow Chinese or mathematics extracurricular books. 39 people borrowed Chinese extracurricular books, and 32 people borrowed math extracurricular books. How many people borrow both Chinese and mathematics extracurricular books?
一个班有45个小学生，统计借课外书的情况是：全班学生都借有语文或数学课外书．借语文课外书的有39人，借数学课外书的有32人．语文、数学两种课外书都借的有多少人．
<gadget id="calculator">32 - 45</gadget>
<output>-13</output>

<gadget id="calculator">39 + (-13)</gadget>
<output>26</output>

<result>26</result>