The ratio of boys to girls in Lai'an Primary School Art Troupe is 2:9. There are 12 boys in the art troupe, how many girls are there?
来安小学艺术团男生和女生人数比是2：9．艺术团男生有12人，女生有多少人？
<gadget id="calculator">9 / 2</gadget>
<output>9/2 = around 4.5</output>

<gadget id="calculator">12 * (9/2)</gadget>
<output>54</output>

<result>54</result>