barrel of oil weighs 35 kilograms. After half of it is used up, the weight of the barrel is 16.5 kilograms. How much is the original weight of the oil in the barrel?
一桶油连桶共重35千克，用去一半后，连桶重16.5千克，原来桶中油重多少千克？
<gadget id="calculator">35 - 16.5</gadget>
<output>18.5</output>

<gadget id="calculator">18.5 * 2</gadget>
<output>37</output>

<result>37</result>