After the price of a commodity is reduced by half, how many pieces can be purchased now with the money that can be used to buy 20 pieces of this commodity.
某种商品降价一半后，原来可以购买该种商品20件的钱，现在可以购买多少件．
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 - (1/2)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">20 / (1/2)</gadget>
<output>40</output>

<result>40</result>