In order to realize the concept of environmental protection, the waste battery recycling team of our school collected 8.25 kilograms of waste batteries in October, 2.1 kilograms more than November, and 1.2 times that in December. How many kilograms of waste were collected in these three months? Battery?
为了实现环保理念，我校废电池回收小组，10月份收集到8.25千克废电池，比11月份多收集2.1千克，12月份收集的是11月份的1.2倍，这三个月共收集了多少千克废电池？
<gadget id="calculator">8.25 - 2.1</gadget>
<output>6.15</output>

<gadget id="calculator">6.15 * 1.2</gadget>
<output>7.38</output>

<gadget id="calculator">8.25 + 6.15 + 7.38</gadget>
<output>21.78</output>

<result>21.78</result>