There are 20 girls in a class. There are 20% fewer girls than boys, and how many fewer girls are there than boys?
某班有女生20人．女生比男生少20%，女生比男生少多少人？
<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">20 / (4/5)</gadget>
<output>25</output>

<gadget id="calculator">25 - 20</gadget>
<output>5</output>

<result>5</result>