There are two barrels of oil, and the mass of the second barrel is 1.5 times that of the first barrel. If 2 kg is taken out from the second barrel and put into the first barrel, the mass of the two barrels of oil is equal. How many kilograms is the first barrel of oil?
有两桶油，第二桶油的质量是第一桶的1.5倍，如果从第二桶中取出2kg放入第一桶中，这时两桶油的质量相等．第一桶油有多少千克？
<gadget id="calculator">2 * 2</gadget>
<output>4</output>

<gadget id="calculator">1.5 - 1</gadget>
<output>0.5</output>

<gadget id="calculator">4 / 0.5</gadget>
<output>8</output>

<result>8</result>