speedboat goes back and forth between two ports of A and B with the same water speed. It takes 6 hours to go there and only 12 hours to return. If the water speed is doubled, how long does it take for this speedboat to make a round trip?
一艘快艇在甲乙两个港口之间往返，水速不变，去时用了6小时，回来只用了12小时，如果水速增大一倍，这艘快艇往返一次需要多少时间？
<gadget id="calculator">24 / 5</gadget>
<output>24/5 = around 4.8</output>

<gadget id="calculator">(24/5) + 24</gadget>
<output>144/5 = around 28.8</output>

<result>144/5 = around 28.8</result>