12 potted flowers are placed on both sides of a road with a length of 220 meters, and both ends are placed. What is the average interval of a potted flower?
在一条路长220米的道路两侧各放了12盆花，两头都放，平均每隔多少米放一盆花？
<gadget id="calculator">12 - 1</gadget>
<output>11</output>

<gadget id="calculator">220 / 11</gadget>
<output>20</output>

<result>20</result>