A motorcycle travels from A to B at a speed of 126 kilometers per hour, arrives at B after 2 hours, and then returns to A in 2.5 hours. What is the average speed of this motorcycle for a round trip?
一辆摩托车以每小时126千米的速度从甲地去乙地，经过2小时到达乙地，然后用2.5小时返回甲地．这辆摩托车往返一次的平均速度是多少？
<gadget id="calculator">126 * 2 * 2</gadget>
<output>504</output>

<gadget id="calculator">2 + 2.5</gadget>
<output>4.5</output>

<gadget id="calculator">504 / 4.5</gadget>
<output>112</output>

<result>112</result>