In Huguang Village this year, herrings accounted for 25% of the total, and silver carp accounted for 20% of the herrings. What percentage of the total is silver carp less than herring?
湖光村今年养的鱼种，青鱼占总数的25%，鲢鱼占青鱼的20%．鲢鱼比青鱼少占总数的百分之几？
<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/4) * (1/5)</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(1/4) - (1/20)</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>