30% of a barrel of oil is used on the first day, 60 kg is used on the second day, half of the oil is used in two days, how much does the barrel of oil weigh?
一桶油第一天用去它的30%，第二天用去60千克，两天正好用去这桶油的一半，这桶油原来重多少千克？
<gadget id="calculator">10 / 0.2</gadget>
<output>50</output>

<result>50</result>