A 30% discount on a commodity, which used to cost 80 yuan, can be reduced by a few yuan now.
一种商品打七折，原来要80元，现在可以少用多少元．
<gadget id="calculator">70 / 100</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">1 - (7/10)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">80 * (3/10)</gadget>
<output>24</output>

<result>24</result>