boat travels 80 kilometers per hour from A to B, and it takes 3 hours to get there. When it comes back, it travels against the current and travels 60 kilometers per hour, how many hours can it reach A? (Solved with proportional knowledge)
船从甲到乙每小时行驶80千米，3小时可以到达，回来时逆流而行，每小时行驶60千米，则几小时可以到达甲？(用比例知识解决)
<gadget id="calculator">80 * 3</gadget>
<output>240</output>

<gadget id="calculator">240 / 60</gadget>
<output>4</output>

<result>4</result>