A cake is 80 yuan after a 20% discount. What is the original price of this cake?
一个蛋糕打八折后是80元，这个蛋糕原价是多少元．
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">80 / (4/5)</gadget>
<output>100</output>

<result>100</result>