Put 20 grams of sugar into 100 grams of water. After two days, the quality of the sugar water is only 100 grams. What is the concentration of the sugar water at this time? How many percent has the concentration increased from the original?
20克糖放入100克水中，放置两天后，糖水质量只有100克，这时糖水的浓度是多少？浓度比原来提高了百分之几？
<gadget id="calculator">20 - 100</gadget>
<output>-80</output>

<gadget id="calculator">100 + (-80)</gadget>
<output>20</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">100 + 20</gadget>
<output>120</output>

<gadget id="calculator">20 / 120</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">(1/5) - (1/6)</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">(1/30) / (1/6)</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>