A passenger car and a freight train meet on the way. The passenger car is 280 meters long and travels 20 meters per second. The truck is 490 meters long and travels 15 meters per second. How long does it take for the two cars to meet and leave completely?
一列客车和一列货车在途中相遇，客车长280米，每秒行20米，货车长490米，每秒行15米，这两车从相遇到完全离开共需多长时间？
<gadget id="calculator">280 + 490</gadget>
<output>770</output>

<gadget id="calculator">20 + 15</gadget>
<output>35</output>

<gadget id="calculator">770 / 35</gadget>
<output>22</output>

<result>22</result>