One day on the way home from school, A and B exchanged the video games they had played. They recalled 20 different games, among which A played 8 and B played 16. How many games did they both play? indivual?
某天的放学路上，甲和乙交流起各自玩过的电子游戏，他们回想起了20个不同的游戏，其中甲玩过8个，乙玩过16个，那么他们都玩过的游戏有几个？
<gadget id="calculator">16 + 8</gadget>
<output>24</output>

<gadget id="calculator">24 - 20</gadget>
<output>4</output>

<result>4</result>