A barrel of oil weighs 40 kilograms. After pouring out (1/3), the weight of the barrel is 28 kilograms. How many kilograms does the oil weigh?
一桶油连桶重40千克，倒出(1/3)后，连桶重28千克，油重多少千克．
<gadget id="calculator">40 - 28</gadget>
<output>12</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">12 / (1/3)</gadget>
<output>36</output>

<result>36</result>