There are 4 grams of salt in a cup of 100 grams of salt water, how many grams of water need to be evaporated to make the salt content of this cup of salt water 8%?
一杯100克的盐水中，有盐4克，现在要使这杯盐水含盐率变为8%，需蒸发多少克水？
<gadget id="calculator">8 / 100</gadget>
<output>2/25 = around 0.08</output>

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

<gadget id="calculator">100 - 50</gadget>
<output>50</output>

<result>50</result>