Put 20 grams of sugar into 100 grams of water and let it stand for three days. Due to evaporation, only 100 grams of sugar water remains. How much is the concentration of sugar water at this time higher than before?
把20克糖放入100克水中，放置三天后，因为蒸发，糖水只剩下100克，这时糖水的浓度比原来提高多少．
<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>