There are 8 people in an extracurricular activity group. There are 6 people who like singing, 4 people like dancing, how many people like both singing and dancing?
某课外活动小组有8个人．喜欢唱歌的有6人，喜欢跳舞的有4人，既喜欢唱歌又喜欢跳舞的有多少人？
<gadget id="calculator">4 - 8</gadget>
<output>-4</output>

<gadget id="calculator">6 + (-4)</gadget>
<output>2</output>

<result>2</result>