Two oil barrels, A and B, are each filled with 15 kilograms of oil. After the salesman sells 14 kilograms, he pours a part from the A barrel with more oil to the B barrel, so that the oil in the B barrel increases by 1 times; and then pours a part from the B barrel Given barrel A, the oil in barrel A is also doubled. At this time, the oil in barrel A is exactly three times the oil in barrel B. So, how many kilograms of oil did the salesperson sell from barrel B?
甲、乙两个油桶各装了15千克油，售货员卖出了14千克后从剩下较多油的甲桶倒一部分给乙桶，使得乙桶油增加l倍；然后从乙桶倒一部分给甲桶，使甲桶油也增加1倍，这时甲桶油恰好是乙桶油的3倍．那么，售货员从乙桶里卖出了多少千克油．
<gadget id="calculator">15 * 2</gadget>
<output>30</output>

<gadget id="calculator">30 - 14</gadget>
<output>16</output>

<gadget id="calculator">3 + 1</gadget>
<output>4</output>

<gadget id="calculator">16 / 4</gadget>
<output>4</output>

<gadget id="calculator">1 + 1</gadget>
<output>2</output>

<gadget id="calculator">3 / 2</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">4 * (3/2)</gadget>
<output>6</output>

<gadget id="calculator">4 + 6</gadget>
<output>10</output>

<gadget id="calculator">10 / 2</gadget>
<output>5</output>

<gadget id="calculator">10 - 5</gadget>
<output>5</output>

<gadget id="calculator">15 - 5</gadget>
<output>10</output>

<result>10</result>