Students from a certain school line up to do exercises, with 30 people standing in each row, and 20 rows can be stood. If there are 6 less people standing in each row, how many more rows can be stood? (Solve with ratio)
某校的同学排队做操，每行站30人，可以站20行．如果每行少站6人，可以多站多少行？(用比例解)
<gadget id="calculator">30 * 20</gadget>
<output>600</output>

<gadget id="calculator">30 - 6</gadget>
<output>24</output>

<gadget id="calculator">600 / 24</gadget>
<output>25</output>

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

<result>5</result>