There is 40 kilograms of sugar water containing sugar (1/5), and it is prepared into sugar water containing sugar (1/4), how many kilograms of water should be evaporated?
现有含糖(1/5)的糖水40千克，把它配制成含糖(1/4)的糖水，应蒸发掉水多少千克？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

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

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

<gadget id="calculator">40 * (4/5)</gadget>
<output>32</output>

<gadget id="calculator">40 - 32</gadget>
<output>8</output>

<result>8</result>