There are several kilograms of alcohol with a concentration of 45%, and then 16 kilograms of alcohol with a concentration of 10% are added. After mixing, the concentration of the alcohol solution is 25%. Question: How many kilograms of alcohol are there now?
有浓度为45%的酒精若干千克，再加入16千克浓度为10%的酒精，混合以后的酒精溶液的浓度为25%，问：现在的酒精有多少千克？
<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/4) * 16</gadget>
<output>4</output>

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

<gadget id="calculator">16 * (1/10)</gadget>
<output>8/5 = around 1.6</output>

<gadget id="calculator">4 - (8/5)</gadget>
<output>12/5 = around 2.4</output>

<gadget id="calculator">45 / 100</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">(9/20) - (1/4)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(12/5) / (1/5)</gadget>
<output>12</output>

<gadget id="calculator">12 + 16</gadget>
<output>28</output>

<result>28</result>