Two engineering teams jointly opened a tunnel, each digging from one end to the middle at the same time. The first team dug 12 meters a day, and the second team dug 15 meters a day. After 8 days, the tunnel was dug through. How long is the tunnel?
两个工程队合开一条隧道，各从一端同时向中间开凿．第一队每天开凿12米，第二队每天开凿15米，经过8天正好凿通，这条隧道长多少米？
<gadget id="calculator">12 + 15</gadget>
<output>27</output>

<gadget id="calculator">27 * 8</gadget>
<output>216</output>

<result>216</result>