There are 30 students in class 2 and 1 participating in two extracurricular activity groups, each of whom participates in at least one activity. If there are 16 people participating in the robot group, and 19 people participating in the aircraft model group. How many people participated in both extracurricular activities groups?
二1班有30名同学参加两个课外活动小组，每人至少参加一项．若参加机器人小组的有16人，参加航模小组的19人．则两个课外活动小组都参加的有多少人？
<gadget id="calculator">16 + 19</gadget>
<output>35</output>

<gadget id="calculator">35 - 30</gadget>
<output>5</output>

<result>5</result>