20 kg of the first salt solution contains 18% salt, and the second salt solution contains 6% salt. How many kilograms of the second salt solution should be added to the first salt solution to obtain a 12% salt solution.
第一种盐子溶液20千克，含盐18%，第二种盐水溶液含量盐6%，问需将第二种盐水溶液多少千克加入第一盐水溶液中，可得到12%的盐水溶液．
<gadget id="calculator">18 / 100</gadget>
<output>9/50 = around 0.18</output>

<gadget id="calculator">20 * (9/50)</gadget>
<output>18/5 = around 3.6</output>

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

<gadget id="calculator">20 * (3/25)</gadget>
<output>12/5 = around 2.4</output>

<gadget id="calculator">(18/5) - (12/5)</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">6 / 100</gadget>
<output>3/50 = around 0.06</output>

<gadget id="calculator">(3/25) - (3/50)</gadget>
<output>3/50 = around 0.06</output>

<gadget id="calculator">(6/5) / (3/50)</gadget>
<output>20</output>

<result>20</result>