The distance between A and B is 114 kilometers. A person starts from A by bicycle, walks on a flat road, and then goes uphill to B. When returning from the original road, it takes 8 hours to travel from point B to point A. It is known that the speed of the bicycle on the flat road is 12 kilometers per hour, the speed uphill is 10 kilometers per hour, and the speed downhill is 15 kilometers per hour. Find the average speed during such a round trip?
甲乙两地相距114千米，某人骑车从甲地出发，先走一段平路后，再上坡到乙地．原路返回时，从乙地到甲地需8小时，已知自行车在平路上的速度为每小时12千米，上坡速度为每小时10千米，下坡速度为每小时15千米，求这样往返一次过程中的平均速度？
<gadget id="calculator">114 / 15</gadget>
<output>38/5 = around 7.6</output>

<gadget id="calculator">8 - (38/5)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(1/12) - (1/15)</gadget>
<output>1/60 = around 0.016667</output>

<gadget id="calculator">(2/5) / (1/60) / 12</gadget>
<output>2</output>

<gadget id="calculator">(2/5) / (1/60)</gadget>
<output>24</output>

<gadget id="calculator">114 - 24</gadget>
<output>90</output>

<gadget id="calculator">90 / 10</gadget>
<output>9</output>

<gadget id="calculator">2 + 9 + 8</gadget>
<output>19</output>

<gadget id="calculator">2 / 19</gadget>
<output>2/19 = around 0.105263</output>

<gadget id="calculator">114 * (2/19)</gadget>
<output>12</output>

<result>12</result>