The distance between A and B is 560 kilometers. A ship sails from A to B for 20 hours. It is known that the ship travels 24 kilometers per hour in still water. How long will it take for the ship to return to A?
甲乙两码头相距560千米，一只船从甲码头顺水航行20小时到达乙码头，已知船在静水中每小时行驶24千米，问这船返回甲码头需几小时？
<gadget id="calculator">560 / 20</gadget>
<output>28</output>

<gadget id="calculator">28 - 24</gadget>
<output>4</output>

<gadget id="calculator">24 - 4</gadget>
<output>20</output>

<result>28</result>