There are two barrels of oil, A and B. The difference between the two barrels is 20 kilograms. (2/7) of the oil in barrel A is equal to (1/3) of the oil in barrel B. How many kilograms of oil is in barrel A?
有甲乙两桶油，两桶内装油量的差是20千克，甲桶油的(2/7)等于乙桶油的(1/3)，求甲桶里有油多少千克？
<gadget id="calculator">7 - 6</gadget>
<output>1</output>

<gadget id="calculator">20 / 1</gadget>
<output>20</output>

<gadget id="calculator">20 * 7</gadget>
<output>140</output>

<result>140</result>