For a bucket of pure water, take out (2/5) kilograms for the first time, and take out the remaining (1/5) for the second time. At this time, the water in the bucket is the same as that taken out. How many kilograms of pure water is in the original barrel? What is the column
一桶纯净水，第一次取出(2/5)千克，第二次取出余下的(1/5)，这时桶内的水与取出的同样多．原来桶内的纯净水有多少千克？列式是多少
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

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

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

<gadget id="calculator">(2/5) / (3/5)</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">(2/3) + (2/5)</gadget>
<output>16/15 = around 1.066667</output>

<result>16/15 = around 1.066667</result>