Teacher Li rides a motorcycle from A to B. He travels 60 kilometers at a speed of 20 kilometers per hour and arrives at point B. Travel 30 kilometers per hour when you come back. So, what is the average speed of the round trip in kilometers?
李老师骑摩托车从甲地到乙地．以每小时20千米的速度行了60千米正好到达乙地．回来时每小时行30千米．那么，往返全程的平均速度是多少千米？
<gadget id="calculator">60 * 2</gadget>
<output>120</output>

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

<gadget id="calculator">60 / 30</gadget>
<output>2</output>

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

<gadget id="calculator">120 / 5</gadget>
<output>24</output>

<result>24</result>