A boatman rowed a boat upstream to a city 110 kilometers away. He traveled 30 kilometers during the day and rested at night. During the rest, the boat would drift 10 kilometers downstream along the current. How many days will it take for the boat to reach its destination?
一船夫划小舟逆流而上去110千米外的某城．他白天行驶了30千米，晚上休息，休息时小舟会顺水流向下游漂走10千米．小舟几天后才能到达目的地？
<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<result>5</result>