A bridge has 9 bridge openings, the total length from the first bridge opening to the ninth bridge opening is 164 meters, and the distance between two adjacent bridge openings is 7 meters, how many meters is the average length of each bridge opening?
一座桥有9个桥洞，从第一个桥洞到第9个桥洞全长164米，相邻两个桥洞之间间隔7米，平均每个桥洞长多少米？
<gadget id="calculator">9 - 1</gadget>
<output>8</output>

<gadget id="calculator">7 * 8</gadget>
<output>56</output>

<gadget id="calculator">164 - 56</gadget>
<output>108</output>

<gadget id="calculator">108 / 9</gadget>
<output>12</output>

<result>12</result>