There are 42 people in class 3 and 4, 20 of them participated in the basketball interest group, 24 of them participated in the art interest group, and 14 of them participated in both groups. How many people did not participate in either of these interest groups?
三4班有42人，其中有20人参加了篮球兴趣小组，有24人参加了美术兴趣小组，有14人两个小组都参加了．这两种兴趣小组都没有参加的有多少人？
<gadget id="calculator">24 - 14</gadget>
<output>10</output>

<gadget id="calculator">20 + 10</gadget>
<output>30</output>

<gadget id="calculator">42 - 30</gadget>
<output>12</output>

<result>12</result>