There are 45 students in class 3 and 1, each of whom has signed up for two interest groups, the technology group or the computer group. Among them, 30 people participated in the science and technology group, and 25 people participated in the computer group. How many people participated in both interest groups?
三1班有45人学生，每人都报名参加了科技组或电脑组两个兴趣小组．其中参加科技组的有30人，参加电脑组的有25人，两个兴趣小组都参加的有多少人？
<gadget id="calculator">30 + 25</gadget>
<output>55</output>

<gadget id="calculator">55 - 45</gadget>
<output>10</output>

<result>10</result>