If 150 grams of salt water with a salt content of 10% turns into a salt water with a salt content of 15%, how many grams of water need to be evaporated?
含盐率为10%的盐水150克，变为含盐率为15%的盐水，需蒸发掉多少克水？
<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">150 * (1/10)</gadget>
<output>15</output>

<gadget id="calculator">15 / 100</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">15 / (3/20)</gadget>
<output>100</output>

<gadget id="calculator">150 - 100</gadget>
<output>50</output>

<result>50</result>