clothing store held a sales promotion, and all clothes were sold at a 20% discount. Aunt Zhang bought a skirt for 320 yuan, how much cheaper than the original one?
某服装商场搞促销活动，所有服装一律八折销售，张阿姨用320元买了一条裙子，比原来便宜多少元？
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">320 / (4/5)</gadget>
<output>400</output>

<gadget id="calculator">400 - 320</gadget>
<output>80</output>

<result>80</result>