Two trains, A and B, depart opposite from each other. Car A travels 120 kilometers per hour, and car B travels 100 kilometers per hour. One hour after car A leaves, car B leaves, and after another 2.5 hours the two cars meet. How many miles is the railway between the two places?
甲、乙两列火车从两地相对开出．甲车每小时行120千米，乙车每小时行100千米．甲车开出1小时后，乙车才开出，又经过2.5小时两车相遇．两地间的铁路长多少千米？
<gadget id="calculator">120 + 100</gadget>
<output>220</output>

<gadget id="calculator">220 * 2.5</gadget>
<output>550</output>

<gadget id="calculator">550 + 120</gadget>
<output>670</output>

<result>670</result>