Uncle Wang likes to ride a bicycle. He often goes to a section of road in the suburbs for exercise. When he goes uphill, the speed is 160 m/min, and it takes 45 minutes. When he returns, it takes only 27 minutes to go downhill. The average speed of the round trip on the road?
王叔叔喜欢骑自行车运动，经常去郊区的一段公路上锻炼，他去的时候上坡，速度是160米/分，要用45分钟，返回时是下坡只用了27分钟，求他在这段路上往返的平均速度？
<gadget id="calculator">45 + 27</gadget>
<output>72</output>

<gadget id="calculator">2 / 72</gadget>
<output>1/36 = around 0.027778</output>

<gadget id="calculator">160 * 45 * (1/36)</gadget>
<output>200</output>

<result>200</result>