After 1/3 of a barrel of oil is used up, there are still 6 liters left. How many liters does this barrel of oil originally have?
一桶油用去(1/3)后，还剩下6升，求这桶油原来有几升？
<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">6 / (2/3)</gadget>
<output>9</output>

<result>9</result>