In Class 1, the girls accounted for the whole class (4/9). In the new semester, 4 girls were transferred out. At this time, the girls accounted for the whole class (2/5). How many girls are there in Class 1?
六1班原来女生占全班人数的(4/9)，新学期转出了4名女生，这时女生占全班人数的(2/5)．六1班现在有女生多少人．
<gadget id="calculator">9 - 4</gadget>
<output>5</output>

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

<gadget id="calculator">5 - 2</gadget>
<output>3</output>

<gadget id="calculator">2 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">(4/5) - (2/3)</gadget>
<output>2/15 = around 0.133333</output>

<gadget id="calculator">4 / (2/15)</gadget>
<output>30</output>

<gadget id="calculator">30 * (2/3)</gadget>
<output>20</output>

<result>20</result>