Take out (1/5) of the oil from barrel A and pour it into barrel B, then the weight of the two barrels of oil is equal, and the weight of the oil in barrel B is equal to ((())/(())) of barrel A.
从甲桶油里取出(1/5)倒入乙桶里，则甲乙两桶油重量相等，原来乙桶里的油的重量相当于甲桶的((())/(()))．
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/5) * 2</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<result>3/5 = around 0.6</result>