A ship travels from A to B at 20 kilometers per hour and arrives in 12 hours. When returning from B to A, it travels 4 kilometers per hour. How many hours can it arrive?
一艘轮船，从甲地开往乙地，每小时行20千米，12小时到达，从乙地返回甲地时，每小时行4千米，几小时可以到达？
<gadget id="calculator">20 * 12</gadget>
<output>240</output>

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

<result>60</result>