When the school organized students to participate in group gymnastics performances, it was originally planned that there would be 25 people standing in each row, and 24 rows should be arranged. Later, considering the overall effect of reducing 5 people in each column, how many columns should be arranged? (Answer with proportional knowledge)
学校组织学生参加团体操表演时，原计划每列站25人，要排24列．后来考虑到整体效果每列减少了5人，那么要排多少列？(用比例知识解答)
<gadget id="calculator">25 * 24</gadget>
<output>600</output>

<gadget id="calculator">25 - 5</gadget>
<output>20</output>

<gadget id="calculator">600 / 20</gadget>
<output>30</output>

<result>30</result>