There are 60 people in class 31, 35 people who can swim and 48 people who can sing. How many people do both?
三1班有60人，会游泳的35人，会唱歌的48人．两种都会的有多少人？
<gadget id="calculator">48 - 60</gadget>
<output>-12</output>

<gadget id="calculator">35 + (-12)</gadget>
<output>23</output>

<result>23</result>