13.5 kilograms of oil are used in a barrel, and 16.8 kilograms remain. How much does the barrel of oil weigh?
一桶油用去13.5千克，还剩16.8千克，这桶油重多少千克？
<gadget id="calculator">13.5 + 16.8</gadget>
<output>30.3</output>

<result>30.3</result>