The number of girls accounts for the whole class (3/4), and the number of boys is equal to the number of girls
女生人数占全班人数的(3/4)，男生人数就相当于女生人数的多少
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 - (3/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/4) / (3/4)</gadget>
<output>1/3 = around 0.333333</output>

<result>1/3 = around 0.333333</result>