The number of girls in the library originally accounted for (1/3), and then 6 girls came in, so the ratio of the number of girls to the total number of books is 4:9. How many girls are there in the library now?
图书室原来女生人数占(1/3)，后来又进来6名女生，这样女生人数和图书总人数的比是4：9．现在图书室有女生多少人？
<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">6 / (3/10)</gadget>
<output>20</output>

<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">1 - (4/9)</gadget>
<output>5/9 = around 0.555556</output>

<gadget id="calculator">(4/9) / (5/9)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">20 * (4/5)</gadget>
<output>16</output>

<result>16</result>