Archie took out a bottle of 100% Huiyuan pure fruit juice from the refrigerator, drank one-fifth of it in one gulp, and then put it back into the refrigerator. The next day, my mother took it out and drank the remaining one-fifth. She felt that it was too strong, so she added water to make it full, and after shaking it well, she planned to drink it tomorrow. On the third day, Archie took out the bottle of juice and drank half of it in one go. He was worried that his mother said he drank too much, so he added some water to make up the juice. I would like to ask: What is the concentration of the juice at this time?
阿奇从冰箱里拿出一瓶100%的汇源纯果汁，一口气喝了五分之一后又放回了冰箱．第二天妈妈拿出来喝了剩下的五分之一，觉得太浓，于是就加水兑满，摇匀之后打算明天再喝．第三天阿奇拿出这瓶果汁，一口气喝得只剩一半了．他担心妈妈说他喝得太多，于是就加了些水把果汁兑满．请问：这时果汁的浓度是多少？
<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">(4/5) * (1/5)</gadget>
<output>4/25 = around 0.16</output>

<gadget id="calculator">32 / 100</gadget>
<output>8/25 = around 0.32</output>

<gadget id="calculator">1 - (1/5) - (4/25) - (8/25)</gadget>
<output>8/25 = around 0.32</output>

<result>8/25 = around 0.32</result>