Xiao Ming rides a bicycle from A to B to deliver a letter. First, he walks uphill for 14 minutes, then walks a 3,000-meter-long flat road, and finally goes downhill in 11 minutes and 40 seconds. It is known that Xiao Ming’s speed when riding uphill, on a flat road, and downhill is 2.5 m/s, 4 m/s, and 6 m/s respectively. Find the time it takes for Xiao Ming to go from point A to point B, and then return to point A ．
小明骑自行车从A地到B地去送信，先走了一段上坡路，用了14分钟，又走了一段3000米长的平路，最后下坡用了11分40秒．已知小明骑车上坡、走平路、下坡时的速度分别为2.5米/秒、4米/秒、6米/秒，求小明从A地到B地，再返回A地所用的时间．
<gadget id="calculator">840 + 750 + 700 + 1_680 + 750 + 350</gadget>
<output>5_070</output>

<gadget id="calculator">5_070 / 60</gadget>
<output>169/2 = around 84.5</output>

<result>169/2 = around 84.5</result>