The number of sixth grade boys is the number of the whole class (2/5), and the number of sixth grade girls is the number of boys ((())/(())).
六年级男生人数是全班人数的(2/5)，六年级女生人数是男生人数的((())/(()))．
<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>

<gadget id="calculator">(3/5) / (2/5)</gadget>
<output>3/2 = around 1.5</output>

<result>3/2 = around 1.5</result>