The original price of a stationery box is 20 yuan, how much is the price after 30% off.
一个文具盒的原价是20元，七折后的价钱是多少元．
<gadget id="calculator">70 / 100</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">20 * (7/10)</gadget>
<output>14</output>

<result>14</result>