The number of girls is the number of boys (2/5), how much less girls than boys.
女生人数是男生的(2/5)，女生比男生少多少．
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<result>3/5 = around 0.6</result>