A barrel of oil weighs 5,000 grams. After one-third of the oil is eaten, there are still 1,000 grams. How many grams is there in the barrel?
一桶油重5000克，吃油的三分之一后，还有1000克，桶有多少克．
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 - (1/3)</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1_000 / (2/3)</gadget>
<output>1_500</output>

<gadget id="calculator">5_000 - 1_500</gadget>
<output>3_500</output>

<result>3_500</result>