A ship sails from port A to port B at a speed of 30 kilometers per hour. Arrive in 12 hours, travel 45 kilometers per hour when returning, how many hours can you arrive? (Answer with proportional knowledge)
一艘轮船从甲港驶往乙港，每小时行30千米．12小时到达，返回时每小时行45千米，几小时可以到达？(用比例知识解答)
<gadget id="calculator">30 * 12</gadget>
<output>360</output>

<gadget id="calculator">360 / 45</gadget>
<output>8</output>

<result>8</result>