A barrel of oil weighs 10 kilograms, and the weight of the barrel after eating half of the oil is 5.5 kilograms. How many kilograms of oil are left in the barrel?
一桶油连桶重10千克，吃掉油的一半后连桶重5.5千克，求桶中还有油多少千克？
<gadget id="calculator">10 - 5.5</gadget>
<output>4.5</output>

<result>4.5</result>