Boys account for 4/7 of the class, and how many girls account for the class.
男生占全班人数的(4/7)，女生占全班人数的多少．
<gadget id="calculator">4 / 7</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">1 - (4/7)</gadget>
<output>3/7 = around 0.428571</output>

<result>3/7 = around 0.428571</result>