Xiaobin walks to the amusement center at a speed of 4 kilometers per hour. Xiaoliang rides a bicycle to chase Xiaobin from the same place 6 hours later than Xiaobin. Xiaoliang travels 12 kilometers per hour. He can catch up with Xiaobin in a few hours Bin?
小斌以每小时4千米的速度步行去游乐中心，小亮比小斌晚6小时骑自行车从同一地点出发去追小斌，小亮每小时行12千米，他几小时可追上小斌？
<result>2</result>