Originally there were 210 passengers on board the passenger ship. After reaching a certain station, 78 people disembarked and 129 boarded. How many people were on board when the ship sailed again?
客船上原来有乘客210人，到某一站后下船78人，上船129人，再开船时船上有多少人？
<gadget id="calculator">210 - 78</gadget>
<output>132</output>

<gadget id="calculator">132 + 129</gadget>
<output>261</output>

<result>261</result>