The price of a commodity is first increased (1/5), and then reduced (1/5), the current price is the original price of the commodity.
一种商品先提价(1/5)，再降价(1/5)，现在的价格是原来商品价格的多少．
<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">(4/5) / 1</gadget>
<output>4/5 = around 0.8</output>

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

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