There are 855 passengers on a train from Beijing to Changsha, 259 people get off the train, and 284 people get on the train. How many people are on the train at this time?
从北京到长沙的某列车上有乘客855人，中途有259人下车，又有284人上车，这时车上有多少人？
<gadget id="calculator">855 - 259</gadget>
<output>596</output>

<gadget id="calculator">596 + 284</gadget>
<output>880</output>

<result>880</result>