Xiaohua rides a bicycle from A to B, and travels 400 meters per minute. After arriving at B, he returns immediately and travels 600 meters per minute. How many meters does Xiaohua travel per minute on average during the round trip?
小华骑车由甲地到乙地，每分钟行驶了400米，到达乙地后立即返回，每分钟行驶了600米，小华往返过程中平均每分钟行驶了多少米．
<gadget id="calculator">1 / 400</gadget>
<output>1/400 = around 0.0025</output>

<gadget id="calculator">1 / 600</gadget>
<output>1/600 = around 0.001667</output>

<gadget id="calculator">(1/400) + (1/600)</gadget>
<output>1/240 = around 0.004167</output>

<gadget id="calculator">2 / (1/240)</gadget>
<output>480</output>

<result>480</result>