class of 30 people participated in the rope skipping competition. At the beginning, 4 people were late and did not participate in the competition. At this time, the average score was 20. Later, these 4 students rushed to the competition venue and jumped 26, 27, 28, and 29 ropes respectively. What is the average score of the class at this time?
某班30人参加跳绳比赛，开始时有4人迟到没有参加比赛，这时平均成绩为20个，后来这4位同学赶到了比赛场地，分别跳了26，27，28，29个．这时全班同学的平均成绩是多少个．
<gadget id="calculator">30 - 4</gadget>
<output>26</output>

<gadget id="calculator">26 * 20</gadget>
<output>520</output>

<gadget id="calculator">520 + 26 + 27 + 28 + 29</gadget>
<output>630</output>

<gadget id="calculator">630 / 30</gadget>
<output>21</output>

<result>21</result>