coat is sold at a 20% discount, a reduction of 80 yuan. What is the original price of the coat?
一件上衣，八折售出，减少了80元，这件上衣的原价是多少．
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">80 / (1/5)</gadget>
<output>400</output>

<result>400</result>