There are 40 students in class 21, 28 students scored 100 points in Chinese in the mid-term exam, 32 students scored 100 points in mathematics, and how many students scored 100 points in both Chinese and mathematics.
二1班有学生40人，期中考试语文得100分的有28人，数学得100分的有32人，语文、数学都得100分的有多少人．
<gadget id="calculator">32 - 40</gadget>
<output>-8</output>

<gadget id="calculator">28 + (-8)</gadget>
<output>20</output>

<result>20</result>