There are two trains, one is 102 meters long and travels 20 meters per second. Another column is 120 meters long and travels 17 meters per second. How many seconds will it take for two cars to move toward each other from the front of the car to the rear of the car.
有两列火车，一列长102米，每秒行20米．另一列长120米，每秒行17米．两车相对而行，从车头相遇到车尾相离，需要多少秒．
<gadget id="calculator">102 + 120</gadget>
<output>222</output>

<gadget id="calculator">20 + 17</gadget>
<output>37</output>

<gadget id="calculator">222 / 37</gadget>
<output>6</output>

<result>6</result>