Xiao Ming goes home from school and rides a bicycle at a speed of 16 kilometers per hour along a certain bus route. Along the way, the bus has a car passing him from behind every 12 minutes, and encounters an oncoming car every 4 minutes. car. If the bus travels non-stop at the same speed at equal intervals, what is the interval between departures of the buses?
小明放学回家沿某公共汽车路线以每小时16千米的速度骑自行车回家，沿途该公共汽车每12分就有一辆车从后面超过他，每4分钟就遇到迎面开来的一辆车．如果公共汽车按相等的时间间隔，以同一速度不停地行驶，那么公共汽车发车时间间隔是多少分？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">(1/4) + (1/12)</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(1/3) / 2</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 / (1/6)</gadget>
<output>6</output>

<result>6</result>