The distance between A and B is 6.6 kilometers. It took Ding Ding 10 hours to go from A to B, and 12 hours to return. What is the average speed of Ding Ding for one round trip?
甲、乙两地相距6.6千米，丁丁从甲地到乙地用了10小时，返回时用了12小时，丁丁往返一次的平均速度是多少？
<gadget id="calculator">6.6 * 2</gadget>
<output>13.2</output>

<gadget id="calculator">10 + 12</gadget>
<output>22</output>

<gadget id="calculator">13.2 / 22</gadget>
<output>0.6</output>

<result>0.6</result>