A bottle of oil weighs 400 kilograms, 20% is used up, and the remaining 20% is added. What is the weight of this bottle of oil now?
一瓶油重400千克，用去20%，再装进余下数量的20%，现在这瓶油重多少克．
<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">400 * (4/5)</gadget>
<output>320</output>

<gadget id="calculator">400 * (4/5) * (1/5)</gadget>
<output>64</output>

<gadget id="calculator">320 + 64</gadget>
<output>384</output>

<gadget id="calculator">384 * 1_000</gadget>
<output>384_000</output>

<result>384_000</result>