A barrel of oil, 30% is used up for the first time, 18 kg more than the first time is used for the second time, and there are 24 kg left. How many kg is the oil in the barrel?
一桶油，第一次用去30%，第二次比第一次多用18千克，还剩24千克，这桶油原来多少千克？
<result>80</result>