There are 38 people in class 31. In the school sports meeting, 20 people participated in the head-on relay race, 25 people participated in the rope skipping competition, 5 people did not participate in the two competitions, and some participated in both the head-on relay race and the rope skipping competition. how many people?
三1班有38人，在校运动会中参加迎面接力赛的有20人，参加跳绳比赛的有25人，两项比赛都没有参加的有5人，既参加迎面接力赛又参加跳绳比赛的有多少人？
<gadget id="calculator">38 - 5</gadget>
<output>33</output>

<gadget id="calculator">25 - 33</gadget>
<output>-8</output>

<gadget id="calculator">20 + (-8)</gadget>
<output>12</output>

<result>12</result>