Xiao Li crosses a mountain. The road is 6 kilometers long. When going up the mountain, he travels 2 kilometers per hour. When going down the mountain, he returns along the same road and travels 3 kilometers per hour. Find the average speed of Xiao Li going up and down the mountain.
小李翻过一座山，山路长6千米，上山时每小时行2千米，下山时沿原路返回，每小时行3千米，求小李上下山的平均速度．
<gadget id="calculator">6 / 2</gadget>
<output>3</output>

<gadget id="calculator">6 / 3</gadget>
<output>2</output>

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

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">6 * (2/5)</gadget>
<output>12/5 = around 2.4</output>

<result>12/5 = around 2.4</result>