There are 45 people in a class, 29 people like sports activities, 23 people like cultural activities, and 5 people are not interested in these two activities. How many people like both kinds of activities?
一个班有45人，喜欢体育活动的有29人，喜欢文艺活动的有23人，有5人对这两项都没有兴趣，求两种活动都喜欢的有多少人．
<gadget id="calculator">45 - 5</gadget>
<output>40</output>

<gadget id="calculator">23 - 40</gadget>
<output>-17</output>

<gadget id="calculator">29 + (-17)</gadget>
<output>12</output>

<result>12</result>