There are 40 kilograms of brine with 8% salt content, how many kilograms of salt must be added to make brine with 20% salt content?
有含盐8%的盐水40千克，要配制成含盐20%的盐水，须加盐多少千克？
<gadget id="calculator">8 / 100</gadget>
<output>2/25 = around 0.08</output>

<gadget id="calculator">1 - (2/25)</gadget>
<output>23/25 = around 0.92</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">(23/25) / (4/5)</gadget>
<output>23/20 = around 1.15</output>

<gadget id="calculator">40 * (23/20)</gadget>
<output>46</output>

<gadget id="calculator">46 - 40</gadget>
<output>6</output>

<result>6</result>