Put a cup of 540 grams of salt water in the sun to dry. The salt in the cup accounts for 1/20 of the salt water. After a few days, the salt content of the salt water in the cup is 12%. How many grams of water evaporate?
把一杯540克的盐水放在阳光下晒，原来杯中盐占盐水的(1/20)，几天后，杯中盐水的含盐率为12%．蒸发掉多少克水？
<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">12 / 100</gadget>
<output>3/25 = around 0.12</output>

<gadget id="calculator">(1/20) / (3/25)</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">540 * (5/12)</gadget>
<output>225</output>

<gadget id="calculator">540 - 225</gadget>
<output>315</output>

<result>315</result>