A tree is planted every 5 meters along one side of a road, and a total of 12 trees are planted (both ends). How long is the road in meters?
沿一条路的一侧每隔5米栽一棵树，一共栽了12棵(两端都有)，这条路长多少米．
<gadget id="calculator">12 - 1</gadget>
<output>11</output>

<gadget id="calculator">11 * 5</gadget>
<output>55</output>

<result>55</result>