There are 45 people in class 31, each of whom likes at least one subject, 28 people like mathematics, 26 people like Chinese, how many people like both Chinese and mathematics?
三1班有45人，每人至少喜欢一门课，喜欢数学的有28人，喜欢语文的有26人，既喜欢语文又喜欢数学的有多少人？
<gadget id="calculator">26 - 45</gadget>
<output>-19</output>

<gadget id="calculator">28 + (-19)</gadget>
<output>9</output>

<result>9</result>