There are 42 people in class 5 and 2, 21 people can play basketball, 17 people can swim, 10 people can neither sport, how many people can play both sports?
五2班有42人，会打篮球的有21人，会游泳的有17人，两种运动都不会的有10人，两种运动都会的有多少人？
<gadget id="calculator">10 - 42</gadget>
<output>-32</output>

<gadget id="calculator">21 + 17 + (-32)</gadget>
<output>6</output>

<result>6</result>