The total weight of a bottle of oil is 5.02 kg. After half of the oil is used up, the weight of the bottle is 2.65 kg. What is the net weight of this bottle of oil?
一瓶油连瓶共重5.02千克，用去一半油后连瓶还重2.65千克，这瓶油净重多少千克．
<gadget id="calculator">5.02 - 2.65</gadget>
<output>2.37</output>

<gadget id="calculator">2.37 * 2</gadget>
<output>4.74</output>

<result>4.74</result>