After the price of a kind of clothing is reduced by 20%, the price is 100 yuan. How much is the original price of this dress
一种服装降价20%后，售价为100元．这种服装原价是多少元
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">100 / (4/5)</gadget>
<output>125</output>

<result>125</result>