A barrel of oil weighs (19/2) kg with the barrel, and after half of it is used, the weight of the barrel with the barrel is (11/2) kg. How many kilograms does the barrel of oil weigh?
一桶油，连桶重(19/2)kg，用去了一半后，连桶重(11/2)kg，这桶油重多少千克？
<gadget id="calculator">19 / 2</gadget>
<output>19/2 = around 9.5</output>

<gadget id="calculator">11 / 2</gadget>
<output>11/2 = around 5.5</output>

<gadget id="calculator">(19/2) - (11/2)</gadget>
<output>4</output>

<gadget id="calculator">4 * 2</gadget>
<output>8</output>

<result>8</result>