It turned out that the ratio of males to females in the school interest group was 6:7. Some girls quit due to special reasons, and 10 boys joined. Now boys account for 80% of the total number. It is known that the number of girls is 10. How many girls quit?
原来学校兴趣小组中男、女人数的比为6：7．部分女生因特殊原因退出，又加入了10名男生，现在男生占总人数的80%，已知现在女生人数为10人，问退出的女生是多少人？
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">10 / (1/5)</gadget>
<output>50</output>

<gadget id="calculator">50 - 10</gadget>
<output>40</output>

<gadget id="calculator">40 - 10</gadget>
<output>30</output>

<gadget id="calculator">30 / 6</gadget>
<output>5</output>

<gadget id="calculator">5 * 7</gadget>
<output>35</output>

<gadget id="calculator">35 - 10</gadget>
<output>25</output>

<result>25</result>