Oil in barrel A is 3.6 kg more than barrel B. If 2 kg is added to barrel B and 1 kg is taken out of barrel A, 30% of the oil in barrel A is 0.7 kg less than 50% of the oil in barrel B. Then How many kilograms is a barrel of oil originally?
甲桶油比乙桶油多3.6千克，如果往乙桶中加入2千克，从甲桶中取出1千克后，现在甲桶里的油的30%比乙桶油的50%少0.7千克，那么甲桶油原有多少千克？
<gadget id="calculator">4.9 + 3.6</gadget>
<output>8.5</output>

<result>8.5</result>