Gardeners plant trees on one side of a road (including the endpoints). The distance between every two trees is 4 meters. A total of 86 trees are planted. How long is the road in meters?
园林工人在一条马路的一边栽树(包括端点)，每2棵树之间的距离是4米，一共栽树86棵，这条马路长多少米．
<gadget id="calculator">86 - 1</gadget>
<output>85</output>

<gadget id="calculator">4 * 85</gadget>
<output>340</output>

<result>340</result>