If the number of girls is less than the number of boys (1/5), then the number of boys is greater than the number of girls.
女生人数比男生人数少(1/5)，则男生人数比女生人数多多少．
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">(1/5) / (4/5)</gadget>
<output>1/4 = around 0.25</output>

<result>1/4 = around 0.25</result>