The ratio of salt to water in 40 grams of salt water is 1:3, how many grams of water should be added to make the salt content of the salt water 20%.
40克盐水中盐与水的比是1：3，要使盐水含盐率为20%，应加水多少克．
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">40 * (1/5)</gadget>
<output>8</output>

<gadget id="calculator">40 * (1/5) * 3</gadget>
<output>24</output>

<gadget id="calculator">40 - 8 - 24</gadget>
<output>8</output>

<gadget id="calculator">(1/5) * 3</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">(1/5) + (3/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">8 / (4/5)</gadget>
<output>10</output>

<result>10</result>