The original price of a coat is 400 yuan. Now it is sold at 20% off the original price. How much is it cheaper?
一件大衣原价是400元，现在按原价的八折出售，便宜了多少元．
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

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

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

<result>80</result>