A ship departs from Port A, travels 24 kilometers per hour along the current, arrives at Port B in 3 hours, and sails against the current to return to Port A in 5 hours. How many kilometers per hour does the ship travel on average for one round trip?
一艘轮船从甲港出发，顺水每小时行24千米，3小时到达乙港，返航时逆水航行用5小时回到甲港．这艘轮船往返一次平均每小时行多少千米？
<gadget id="calculator">3 + 5</gadget>
<output>8</output>

<gadget id="calculator">2 / 8</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">24 * 3 * (1/4)</gadget>
<output>18</output>

<result>18</result>