A plane travels from A to B in 3 hours at a speed of 500 kilometers per hour, and only takes 2 hours to return. What is the average round-trip speed of this plane?
一架飞机以每小时500千米的速度，由甲地飞往乙地用了3小时，返回时只用了2小时，这架飞机的往返的平均速度是多少？
<gadget id="calculator">500 * 3 * 2</gadget>
<output>3_000</output>

<gadget id="calculator">3 + 2</gadget>
<output>5</output>

<gadget id="calculator">3_000 / 5</gadget>
<output>600</output>

<result>600</result>