A barrel of oil is used up (1/3), and there are 12 kilograms left. How many kilograms is this barrel of oil?
一桶油用去它的(1/3)，还剩下12千克，这桶油有多少千克．
<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">12 / (2/3)</gadget>
<output>18</output>

<result>18</result>