A down jacket is on sale at 30% off, and now each piece is 280 yuan, how much cheaper the current price is than the original price.
一件羽绒服打七折出售，现在每件280元，现价比原价便宜多少元．
<gadget id="calculator">70 / 100</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">280 / (7/10)</gadget>
<output>400</output>

<gadget id="calculator">400 - 280</gadget>
<output>120</output>

<result>120</result>