The selling price of a piece of clothing after 30% off is 280 yuan. What is the original price of this piece of clothing?
一件衣服七折后售价是280元，这件衣服原价是多少元．
<gadget id="calculator">70 / 100</gadget>
<output>7/10 = around 0.7</output>

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

<result>400</result>