On one side of a 180-meter-long tunnel, a total of 16 energy-saving lamps (both ends are installed) are installed from the beginning to the end. How many meters are installed on average for a lamp?
在一条长180米的隧道一侧，从头到尾一共安装了16盏节能灯(两头都安装)，平均每隔多少米安装一盏灯？
<gadget id="calculator">16 - 1</gadget>
<output>15</output>

<gadget id="calculator">180 / 15</gadget>
<output>12</output>

<result>12</result>