If the price of an electrical appliance is increased by 10%, and then the price is reduced by 20%, it will be the original price.
一件电器提价10%，再降价20%，则是原价的多少．
<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 + (1/10)</gadget>
<output>11/10 = around 1.1</output>

<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 * (11/10) * (4/5)</gadget>
<output>22/25 = around 0.88</output>

<result>22/25 = around 0.88</result>