There were originally 408 people on the train, but 29 people got off and 128 got on the train after arriving at the station. How many people were on the train when it drove again?
火车上原有408人，到站后有29人下车，有128人上车．再开车时火车上有多少人？
<gadget id="calculator">408 - 29</gadget>
<output>379</output>

<gadget id="calculator">379 + 128</gadget>
<output>507</output>

<result>507</result>