The original price of a commodity is 36 yuan, how much is the 20% discount.
一种商品原价36元，八折优惠是多少元．
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">36 * (4/5)</gadget>
<output>144/5 = around 28.8</output>

<result>144/5 = around 28.8</result>