A bucket of water with the bucket weighs 6.5 kilograms. After half of the water is used, the bucket still weighs 4 kilograms. How many kilograms does the bucket weigh?
一桶水连桶共重6.5千克，用去水一半后，连桶还重4千克，桶重多少千克？
<gadget id="calculator">6.5 - 4</gadget>
<output>2.5</output>

<gadget id="calculator">4 - 2.5</gadget>
<output>1.5</output>

<result>1.5</result>