How many grams of water must be evaporated from 150 grams of 10% brine to make 25% brine?
浓度为10%的盐水150克，为了制成浓度为25%的盐水，需要从中蒸发掉多少克水？
<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/10) / (1/4)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">150 * (2/5)</gadget>
<output>60</output>

<gadget id="calculator">150 - 60</gadget>
<output>90</output>

<result>90</result>