Girls are 90% of boys in the math competition. If there are 9 more girls participating, the number of girls is more than boys (1/5). How many girls are participating in the math competition?
参加数学竞赛，女生是男生的90%，如果女生再有9人参加，则女生人数比男生多(1/5)，参加数学竞赛的女生有多少人？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">(1/5) - (9/10)</gadget>
<output>-7/10 = around -0.7</output>

<gadget id="calculator">1 + (-7/10)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">9 / (3/10)</gadget>
<output>30</output>

<gadget id="calculator">30 * (9/10)</gadget>
<output>27</output>

<result>27</result>