There is a barrel of oil, 20% of the whole barrel is taken out for the first time, and 5 kg more than the first time is taken out for the second time, leaving 19 kg, how much is the original oil in kilograms? (solution with equation)
有一桶油，第一次取出全桶的20%，第二次比第一次多取出5千克，还剩19千克，求原有油多少千克？(用方程式解)
<result>40</result>