The price of a basketball is reduced by 20% to 80 yuan. How much is the original price of this basketball?
一个篮球降价20%后是80元，这个篮球原价是多少元？
<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">80 / (4/5)</gadget>
<output>100</output>

<result>100</result>