To dilute 20kg of sugar water with 15% sugar content into sugar water with 5% sugar content, how many kilograms of water do you need to add?
将20kg含糖15%的糖水，稀释成含糖5%的糖水，需要加水多少千克？
<gadget id="calculator">15 / 100</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">5 / 100</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(3/20) / (1/20)</gadget>
<output>3</output>

<gadget id="calculator">20 * 3</gadget>
<output>60</output>

<gadget id="calculator">60 - 20</gadget>
<output>40</output>

<result>40</result>