A barrel of oil is 25 kilograms, 20% has been consumed, how many kilograms are left?
一桶油25千克，已经吃了20%，还剩多少千克？
<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">25 * (4/5)</gadget>
<output>20</output>

<result>20</result>