A barrel of oil weighs 52.2kg. After half of the oil is poured out, the weight of the barrel is 27.2kg. How many kilograms does the barrel weigh?
一桶油连桶共重52.2kg，倒出一半油后，连桶重27.2kg，桶重多少千克？
<gadget id="calculator">52.2 - 27.2</gadget>
<output>25</output>

<gadget id="calculator">25 * 2</gadget>
<output>50</output>

<gadget id="calculator">52.2 - 50</gadget>
<output>2.2</output>

<result>2.2</result>