A barrel of oil weighs 9.2 kilograms. After half of it is used, there are 5.2 kilograms left. What is the weight of the barrel?
一桶油连桶重9.2千克，用去一半后，还剩5.2千克，桶重是多少千克．
<gadget id="calculator">9.2 - 5.2</gadget>
<output>4</output>

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

<gadget id="calculator">9.2 - 8</gadget>
<output>1.2</output>

<result>1.2</result>