A bag of 500 grams of sugar, after eating 20% and adding another 20%, what is the weight of the bag of sugar now?
一袋糖500克，吃掉20%后，再增加20%，这袋糖现在重多少克．
<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">1 + (1/5)</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">500 * (4/5) * (6/5)</gadget>
<output>480</output>

<result>480</result>