train of passenger trains is 190 meters long, and a train of freight trains is 260 meters long. The two trains are traveling towards each other at speeds of 90 kilometers per hour and 72 kilometers per hour.
一列客车长190米，一列货车长260米，两车分别以每小时90千米和72千米的速度相向行驶，在双轨道路上交会时，从车头相遇到车尾相遇共需多少时间．
<gadget id="calculator">190 + 260</gadget>
<output>450</output>

<gadget id="calculator">25 + 20</gadget>
<output>45</output>

<gadget id="calculator">450 / 45</gadget>
<output>10</output>

<result>10</result>