For a commodity, the price is reduced by 20% when summer comes, and the price is increased by 20% based on the summer price when winter comes, then the current price is the price reduction in summer
一种商品，夏季来临时降价20%，冬季来临时又在夏季售价的基础上涨价20%，则现价是夏季降价的多少
<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 + (1/5)</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">(6/5) / 1</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">1 * (4/5) * (6/5)</gadget>
<output>24/25 = around 0.96</output>

<result>24/25 = around 0.96</result>