Two barrels of oil, A and B, have the same quality. 60kg is poured out of barrel A, and 40kg is poured out of barrel B. The result is that the mass of barrel B is three times that of barrel A. How much is the weight of the oil in barrels A and B? ?
A、B两桶油质量相等，从A桶里倒出60kg，从B桶倒出40kg，结果B桶中的质量是A桶中的3倍，原来A、B桶里的油各重多少千克？
<gadget id="calculator">3 * 60</gadget>
<output>180</output>

<gadget id="calculator">180 - 40</gadget>
<output>140</output>

<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">140 / 2</gadget>
<output>70</output>

<result>70</result>