A bucket of water weighs 12 kilograms. When it is half full, the bucket and water weigh 7 kilograms. How many kilograms does the bucket of water weigh?
一桶水连桶重12千克，到出一半后，桶和水共重7千克，这桶水原来有多少千克？
<gadget id="calculator">12 - 7</gadget>
<output>5</output>

<gadget id="calculator">5 * 2</gadget>
<output>10</output>

<result>10</result>