A bottle of salt water weighs 400 grams, and the ratio of salt to water is 1:19. Now to dilute the bottle of salt water so that the ratio of salt to water is 1:25, how many grams of water should be added?
一瓶盐水重400克，其中盐和水的比是1：19，现在要把这瓶盐水冲淡，使得盐和水的比是1：25，需加水多少克？
<gadget id="calculator">1 + 19</gadget>
<output>20</output>

<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">400 * (1/20)</gadget>
<output>20</output>

<gadget id="calculator">1 / 25</gadget>
<output>1/25 = around 0.04</output>

<gadget id="calculator">400 - 20</gadget>
<output>380</output>

<gadget id="calculator">(1/25) * 380</gadget>
<output>76/5 = around 15.2</output>

<gadget id="calculator">20 - (76/5)</gadget>
<output>24/5 = around 4.8</output>

<gadget id="calculator">(24/5) / (1/25)</gadget>
<output>120</output>

<result>120</result>