A row of trees is planted on both sides of a 75-meter-long road. If trees are planted at the end and the distance between every two adjacent trees is 15 meters, how many trees should be planted in total?
在一条长75米的大路两旁栽一行树，如果首尾都种树，并且每相邻的两棵树之间的距离都是15米，一共需要栽多少棵树？
<gadget id="calculator">75 / 15</gadget>
<output>5</output>

<gadget id="calculator">5 + 1</gadget>
<output>6</output>

<gadget id="calculator">6 * 2</gadget>
<output>12</output>

<result>12</result>