train departs from Changsha to Guangzhou, traveling 70 kilometers per hour. One hour after the freight train leaves, a passenger train departs from Guangzhou to Changsha, traveling 60 kilometers per hour. After 4.5 hours, the passenger train meets the freight train. How long is the railway from Changsha to Guangzhou?
一列火车从长沙开往广州，每小时行70千米，这列货车开出1小时后，一列客车从广州出发开往长沙，每小时行60千米，客车经4.5小时后，与货车相遇．长沙到广州的铁路长多少千米？
<gadget id="calculator">60 + 70</gadget>
<output>130</output>

<gadget id="calculator">130 * 4.5</gadget>
<output>585</output>

<gadget id="calculator">70 + 585</gadget>
<output>655</output>

<result>655</result>