Two trains leave from the east and the west. The lengths of the two trains are 125 meters and 115 meters, and the speeds are 12 m/s and 18 m/s.
两辆列车从东西两地开出，两车车长为125米和115米，车速为12米/秒和18米/秒，从两车车头相遇到车尾分开需要多少秒？
<gadget id="calculator">125 + 115</gadget>
<output>240</output>

<gadget id="calculator">22 + 18</gadget>
<output>40</output>

<gadget id="calculator">240 / 40</gadget>
<output>6</output>

<result>6</result>