Chen Conghui went to climb Baiyun Mountain on Sunday. The speed of going up the mountain was 4 kilometers per hour. After reaching the top of the mountain, he immediately descended from the original road at a speed of 6 kilometers per hour and returned to the original starting point. How many kilometers do you travel?
陈聪慧星期天去登白云山，上山的速度是每小时4千米，到达山顶后立即从原路以每小时6千米的速度下山，回到原出发地，陈聪慧这次登山全程平均每小时行多少千米．
<gadget id="calculator">1 * 2</gadget>
<output>2</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">(1/4) + (1/6)</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">2 / (5/12)</gadget>
<output>24/5 = around 4.8</output>

<result>24/5 = around 4.8</result>