A bucket of water with the bucket weighs 45 kg, and after half of the water is poured out, the weight of the bucket is 24 kg. How many kilograms would the empty bucket weigh if all the water was poured out?
一桶水连桶重45千克，倒去一半水后，连桶重24千克．如果把水全部倒完，空桶重多少千克？
<gadget id="calculator">45 - 24</gadget>
<output>21</output>

<gadget id="calculator">21 * 2</gadget>
<output>42</output>

<gadget id="calculator">45 - 42</gadget>
<output>3</output>

<result>3</result>