There are 40 trees on one side of a road, and the distance between every two trees is 5 meters. How long is the road?
一条路的一侧有40棵树，每两棵树的间隔是5米，这条路长多少米？
<gadget id="calculator">40 - 1</gadget>
<output>39</output>

<gadget id="calculator">39 * 5</gadget>
<output>195</output>

<result>195</result>