Add 5 grams of sugar to a cup of sugar water containing 20% sugar, how many grams of water should be added to keep the sugar content of this cup of sugar water unchanged?
向一杯含糖20%的糖水里再加5克糖，要使这杯糖水的含糖率不变，需加水多少克．
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

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

<gadget id="calculator">25 - 5</gadget>
<output>20</output>

<result>20</result>