Five (1,50 people participated in Chinese and mathematics competitions, all 30 people participated in Chinese competitions, 38 people participated in mathematics competitions, 2 people did not participate in both subjects, how many people participated in both subjects?
五(1,50人参加语文和数学竞赛，参加语文竞赛所有30人，参加数学竞赛的有38人，两科都不参加的有2人，两科都参加的有多少人？
<gadget id="calculator">50 - 2</gadget>
<output>48</output>

<gadget id="calculator">38 - 48</gadget>
<output>-10</output>

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

<result>20</result>