If the price of a drug is reduced by 35% first, and then the price is reduced by 20% after the price reduction, the current price is the price before the price reduction.
一种药品先降价35%，接着又按降价后的价格又降低了20%，则现在的价钱是未降价前价格的多少．
<gadget id="calculator">35 / 100</gadget>
<output>7/20 = around 0.35</output>

<gadget id="calculator">1 - (7/20)</gadget>
<output>13/20 = around 0.65</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">(13/20) * (4/5)</gadget>
<output>13/25 = around 0.52</output>

<result>13/25 = around 0.52</result>