Dongshan Township planted trees along one side of the road. From one end, a tree was planted every 6 meters. A total of 15 trees were planted. How many meters is the distance from the first tree to the last tree?
东山乡沿公路的一侧栽树，从一端开始每隔6米栽一棵树，一共栽了15棵，从第一棵到最后一棵的距离有多少米．
<gadget id="calculator">15 - 1</gadget>
<output>14</output>

<gadget id="calculator">14 * 6</gadget>
<output>84</output>

<result>84</result>