There is a train leaving Los Angeles going straight to New York at a speed of 140 kilometers per hour, while another train is traveling from New York to Los Angeles at a speed of 160 kilometers per hour. If a bird starts at the same time as two trains at a speed of 30 kilometers per hour, departs from Los Angeles, returns after meeting another train, and goes back and forth between the two trains until the two trains meet. It is known that the railway from Los Angeles to New York is 4,500 kilometers long. May I ask: How many kilometers did this bird fly?
有一列火车以每小时140千米的速度离开洛杉矶直奔纽约，同时，另一辆火车以每小时160千米的速度从纽约开往洛杉矶．如果有一只鸟以每小时30千米的速度和两列火车同时启动，从洛杉矶出发，碰到另一列火车后返回，往返在两列火车之间，直到两列火车相遇为止．已知洛杉矶到纽约的铁路长4500千米，请问：这只小鸟飞行了多少千米？
<gadget id="calculator">140 + 160</gadget>
<output>300</output>

<gadget id="calculator">4_500 / 300</gadget>
<output>15</output>

<gadget id="calculator">15 * 30</gadget>
<output>450</output>

<result>450</result>