The distance between port A and port B is 120 kilometers, the speed of the ship is 35 kilometers per hour, and the speed of water is 5 kilometers per hour. How many hours does it take for a passenger to go back and forth between ports A and B by this ship?
甲港与乙港相距120千米，船速为每小时35千米，水速为每小时5千米，一个旅客乘该船在甲、乙两港来回一趟共需多少小时．
<gadget id="calculator">35 + 5</gadget>
<output>40</output>

<gadget id="calculator">120 / 40</gadget>
<output>3</output>

<gadget id="calculator">35 - 5</gadget>
<output>30</output>

<gadget id="calculator">120 / 30</gadget>
<output>4</output>

<gadget id="calculator">3 + 4</gadget>
<output>7</output>

<result>7</result>