There are 54 students on the playground, among them (7/9) are male students. How many girls are there?
操场上有54名同学，其中(7/9)是男同学．女生有多少人？
<gadget id="calculator">7 / 9</gadget>
<output>7/9 = around 0.777778</output>

<gadget id="calculator">54 * (7/9)</gadget>
<output>42</output>

<gadget id="calculator">54 - 42</gadget>
<output>12</output>

<result>12</result>