ship sails from port A to port B at 15 kilometers per hour and arrives in 20 hours. The speed when returning is 25 kilometers per hour, how many hours will it take to return?
一艘轮船从甲港到乙港，每小时航行15千米，20小时到达．返回时的速度是每小时25千米，返回需要几小时？
<gadget id="calculator">20 / 25</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">15 * (4/5)</gadget>
<output>12</output>

<result>12</result>