For a commodity, first increase the price (1/5), then reduce the price (1/5), how much higher the original price is than the current price
一件商品，先提价(1/5)，再降价(1/5)，原价比现价高多少
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

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

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

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

<gadget id="calculator">1 - (24/25)</gadget>
<output>1/25 = around 0.04</output>

<gadget id="calculator">(1/25) / (24/25)</gadget>
<output>1/24 = around 0.041667</output>

<result>1/24 = around 0.041667</result>