A 20% reduction in the number of girls in a class equals the number of boys. It is true that there are more girls than boys below.
某班女生人数减少20%就与男生人数相等．下面女生比男生多多少是正确的．
<gadget id="calculator">20 / 100</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>