500 grams of 10% salt water, how many grams of water must be evaporated to make the salt content of the salt water 16%.
500克含盐10%的盐水，要蒸发掉多少克水，才能使盐水的含盐率变为16%．
<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

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

<gadget id="calculator">16 / 100</gadget>
<output>4/25 = around 0.16</output>

<gadget id="calculator">50 / (4/25)</gadget>
<output>625/2 = around 312.5</output>

<gadget id="calculator">500 - (625/2)</gadget>
<output>375/2 = around 187.5</output>

<result>375/2 = around 187.5</result>