200 kg of salt water contains 40% salt, and how many kilograms of water are added, the salt content of salt water is 25%.
在200千克盐水中含盐40%，再加入多少千克水，盐水的含盐率为25%．
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

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

<gadget id="calculator">(2/5) / (1/4)</gadget>
<output>8/5 = around 1.6</output>

<gadget id="calculator">200 * (8/5)</gadget>
<output>320</output>

<gadget id="calculator">320 - 200</gadget>
<output>120</output>

<result>120</result>