A barrel of oil uses 10.2 kilograms, and the rest is 2.8 times that used, how many kilograms of oil are left?
一桶油用去10.2千克，剩下的是用去的2.8倍，剩下多少千克油？
<gadget id="calculator">10.2 * 2.8</gadget>
<output>28.56</output>

<result>28.56</result>