For an electrical appliance, first raise the price (1/6), then lower the price ((())/(())), the current price and the original price will be the same.
一件电器，先提价(1/6)，再降价((())/(()))，现价和原价就一样了．
<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 + (1/6)</gadget>
<output>7/6 = around 1.166667</output>

<gadget id="calculator">(1/6) / (7/6)</gadget>
<output>1/7 = around 0.142857</output>

<result>1/7 = around 0.142857</result>