The road from the foot of the mountain to the top of the mountain is 4000 meters long. It took Xiaoqiang 45 minutes to go up the mountain and 35 minutes to go down the mountain along the original road. Find the average speed of Xiaoqiang going up and down the mountain.
从山脚到山顶的路长4000米，小强上山用了45分钟，沿原路下山用了35分钟，求小强上山和下山的平均速度．
<gadget id="calculator">4_000 * 2</gadget>
<output>8_000</output>

<gadget id="calculator">45 + 35</gadget>
<output>80</output>

<gadget id="calculator">8_000 / 80</gadget>
<output>100</output>

<result>100</result>