If a road is 180 meters long and 31 trees are planted from the beginning to the end, what is the distance between every two trees?
如果一条路长180米，从头到尾共植树31棵，每两棵树之间相隔多少米．
<gadget id="calculator">31 - 1</gadget>
<output>30</output>

<gadget id="calculator">180 / 30</gadget>
<output>6</output>

<result>6</result>