The winding road from the bottom of the mountain to the top of the mountain is 3 kilometers long. The uphill travel is 2 kilometers per hour, and the downhill travel is 3 kilometers per hour. What is the average speed of the person going up and down the mountain in kilometers per hour?
从山下到山顶的盘山公路长3千米，上山每小时行2千米，下山每小时行3千米，他上、下山的平均速度是每小时多少千米．
<gadget id="calculator">3 * 2</gadget>
<output>6</output>

<gadget id="calculator">3 / 2</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">3 / 3</gadget>
<output>1</output>

<gadget id="calculator">(3/2) + 1</gadget>
<output>5/2 = around 2.5</output>

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

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