Ports A and B are located upstream and downstream of the river respectively, and are 60 kilometers apart. It takes 4 hours for a fishing boat to sail from Port A to Port B. It is known that the speed of the boat is twice the speed of the water. Then the next day How many hours does it take for the ship to sail from port B to port A?
甲、乙两个港口分别位于河流的上游和下游，且相距60千米，一艘渔船从甲港驶往乙港用了4小时，已知船速为水速的2倍，那么第二天船从乙港驶往甲港要多少个小时？
<gadget id="calculator">60 / 4</gadget>
<output>15</output>

<gadget id="calculator">1 + 2</gadget>
<output>3</output>

<gadget id="calculator">15 / 3</gadget>
<output>5</output>

<gadget id="calculator">5 * 2</gadget>
<output>10</output>

<gadget id="calculator">10 - 5</gadget>
<output>5</output>

<gadget id="calculator">60 / 5</gadget>
<output>12</output>

<result>12</result>