There were originally 840 passengers on the subway. After arriving at Huangge Station, 85 people got off and 138 people got on. How many passengers are there on the subway now?
地铁上原有乘客840人，到达黄阁站后，有85人下车，又上来了138人，现在地铁上有多少个乘客？
<gadget id="calculator">840 - 85</gadget>
<output>755</output>

<gadget id="calculator">755 + 138</gadget>
<output>893</output>

<result>893</result>