The number of girls in the sixth grade is 80% of the number of boys. If 8 girls are replaced by boys, the number of girls is 50% of the number of boys. How many girls are there?
六年级的女生人数是男生人数的80%，如果将8名女生换成男生，则女生人数是男生人数的50%，原来有女生几人？
<gadget id="calculator">4 + 5</gadget>
<output>9</output>

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

<gadget id="calculator">1 + 2</gadget>
<output>3</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(4/9) - (1/3)</gadget>
<output>1/9 = around 0.111111</output>

<gadget id="calculator">8 / (1/9)</gadget>
<output>72</output>

<gadget id="calculator">72 * (4/9)</gadget>
<output>32</output>

<result>32</result>