The two barrels of oil in A and B are 80 kg in total. After pouring (1/5) from barrel A into barrel B, the two barrels have the same weight. How many kilograms does barrel B weigh?
甲乙两桶油共80千克，从甲桶倒出(1/5)放入乙桶后，两桶同样重．原来乙桶重多少千克？
<gadget id="calculator">80 / 2</gadget>
<output>40</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">40 / (4/5)</gadget>
<output>50</output>

<gadget id="calculator">80 - 50</gadget>
<output>30</output>

<result>30</result>