A gift of 80 yuan is sold at a 30% discount, which is how much cheaper than the original price.
一件礼品80元，打7折出售，比原价便宜了多少元．
<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>