In the comprehensive practical activity group of the school, girls accounted for 9/20 of the whole group. Later, 16 boys were added. At this time, girls accounted for 1/4 of the whole group. How many girls are there in this comprehensive practical activity group?
学校综合实践活动小组中女生占全组人数的(9/20)，后来又增加16名男生，这时女生占全组人数的(1/4)，这个综合实践活动小组有女生多少人？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">16 * (1/4)</gadget>
<output>4</output>

<gadget id="calculator">9 / 20</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">(9/20) - (1/4)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">4 / (1/5)</gadget>
<output>20</output>

<gadget id="calculator">20 * (9/20)</gadget>
<output>9</output>

<result>9</result>