Each of the students in Class 1 of the fourth grade participates in sports and art activities. There are 15 people participating in sports activities, 23 people participating in art activities, and 8 of them participated in both sports and art activities. How many students are there in Class 1 of the fourth grade?
四年级1班学生每人都参加体育和艺术活动．参加体育活动的有15人，参加艺术活动的有23人，其中有8人体育、艺术活动都参加，四年级1班一共有多少名学生．
<gadget id="calculator">23 - 8</gadget>
<output>15</output>

<gadget id="calculator">15 + 15</gadget>
<output>30</output>

<result>30</result>