The ratio of the number of boys to the number of girls in a class is 7:5, and the number of girls accounts for the number of students in the class.
某班男生人数和女生人数的比为7：5，女生人数占全班人数的多少．
<gadget id="calculator">7 + 5</gadget>
<output>12</output>

<gadget id="calculator">5 / 12</gadget>
<output>5/12 = around 0.416667</output>

<result>5/12 = around 0.416667</result>