train body is 240 meters long and its speed is 15 meters per second; B train body is 360 meters long and its speed is 25 meters per second. How many seconds does it take for two cars to move towards each other on a double-track track from the front of the car to the rear of the car?
甲火车车身长240米，车速是每秒15米；乙火车车身长360米，车速是每秒25米．两车在双轨轨道上相向而行，从车头相遇到车尾相离要用多少秒钟？
<gadget id="calculator">240 + 360</gadget>
<output>600</output>

<gadget id="calculator">15 + 25</gadget>
<output>40</output>

<gadget id="calculator">600 / 40</gadget>
<output>15</output>

<result>15</result>