A barrel of oil weighs 12.65 kilograms. After half of it is used up, the barrel still weighs 6.85 kilograms. How many kilograms of oil are in the original barrel?
一桶油连桶共重12.65千克，用去一半后，连桶还重6.85千克，原来的桶里有油多少千克？
<gadget id="calculator">12.65 - 6.85</gadget>
<output>5.8</output>

<gadget id="calculator">5.8 * 2</gadget>
<output>11.6</output>

<result>11.6</result>