A bucket of water with the bucket weighs 10.4 kilograms. After half of the water is poured out, the bucket with the bucket weighs 6.5 kilograms. How much does the bucket weigh?
一桶水连桶重10.4千克，倒去一半水后，连桶重6.5千克，问桶重多少千克？
<gadget id="calculator">10.4 - 6.5</gadget>
<output>3.9</output>

<gadget id="calculator">3.9 * 2</gadget>
<output>7.8</output>

<gadget id="calculator">10.4 - 7.8</gadget>
<output>2.6</output>

<result>2.6</result>