The waterway from A to B is 375 kilometers long, the flow speed of the river is 5 kilometers per hour, and a passenger ship travels 20 kilometers per hour in still water. How many hours does it take to go back and forth between A and B?
从甲地到乙地的水路有375千米，江水的流速是每小时5千米，一艘客轮在静水中每小时行驶20千米．它在甲、乙两地往返一次需要多少小时．
<gadget id="calculator">20 + 5</gadget>
<output>25</output>

<gadget id="calculator">375 / 25</gadget>
<output>15</output>

<gadget id="calculator">20 - 5</gadget>
<output>15</output>

<gadget id="calculator">375 / 15</gadget>
<output>25</output>

<gadget id="calculator">15 + 25</gadget>
<output>40</output>

<result>40</result>