Supermarket promotion, a desk lamp is priced at 72 yuan after a 20% discount. What is the original price of this desk lamp?
超市促销，一盏台灯打八折后售价72元，这盏台灯的原价是多少．
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">72 / (4/5)</gadget>
<output>90</output>

<result>90</result>