There are 2 kg of sugar water containing 15% sugar and 3 kg of sugar water containing 20% sugar. Now mix the two types of sugar water to make the concentration 10%. How many kg of water do you need to add?
现有含糖15%的糖水2千克和含糖20%的糖水3千克，现将两种糖水混合使其浓度为10%，需要加水多少千克？
<gadget id="calculator">15 / 100</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">2 * (3/20)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

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

<gadget id="calculator">(3/10) + (3/5)</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">10 / 100</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(9/10) / (1/10)</gadget>
<output>9</output>

<gadget id="calculator">2 + 3</gadget>
<output>5</output>

<gadget id="calculator">9 - 5</gadget>
<output>4</output>

<result>4</result>