After 500 grams of mushrooms with a water content of 98% are dried, the water content drops to 20%, and how many grams of water evaporate.
500克含水98%的蘑菇晾晒后，含水率下降到20%，蒸发掉了多少克水．
<gadget id="calculator">98 / 100</gadget>
<output>49/50 = around 0.98</output>

<gadget id="calculator">1 - (49/50)</gadget>
<output>1/50 = around 0.02</output>

<gadget id="calculator">500 * (1/50)</gadget>
<output>10</output>

<gadget id="calculator">20 / 100</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">10 / (4/5)</gadget>
<output>25/2 = around 12.5</output>

<gadget id="calculator">500 - (25/2)</gadget>
<output>975/2 = around 487.5</output>

<result>975/2 = around 487.5</result>