On a road, Xiao Ming rides a bicycle and goes in the same direction as Xiao Guang. Xiao Ming rides a bicycle twice as fast as Xiao Guang. Every 10 minutes, a bus passes Xiao Guang, and every 15 minutes, a bus passes Xiao Ming. It is known that a bus departs from the departure station at the same interval each time. How many minutes is the interval between two adjacent buses?
在一条马路上，小明骑车与小光同向而行，小明骑车速度是小光的2倍，每隔10分钟有一辆公共汽车超过小光，每隔15分钟有一辆公共汽车超过小明．已知公共汽车从始发站每次间隔同样的时间发一辆车，请问相邻两车间隔几分钟？
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(1/10) - (1/15)</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">(1/30) / 2</gadget>
<output>1/60 = around 0.016667</output>

<gadget id="calculator">(1/10) + (1/60)</gadget>
<output>7/60 = around 0.116667</output>

<gadget id="calculator">1 / (7/60)</gadget>
<output>60/7 = around 8.571429</output>

<result>60/7 = around 8.571429</result>