A row of small trees was planted on one side of the road. The original distance between each two classes was 5 meters. If you want to change the distance between each two trees to 8 meters, except for the first tree that does not need to be moved, how many meters should there be? There is another tree far away, don't move it.
马路的一边栽了一行小树，原来每两课之间的距离是5米，如果要将每两棵之间的距离改为8米，除第一棵不需要移动外，至少再隔多少米远又有一棵不要移．
<gadget id="calculator">2 * 2 * 2 * 5</gadget>
<output>40</output>

<result>40</result>