A tree is planted every 6 meters on both sides of a road, and a total of 180 trees are planted. If trees are planted at both ends, how long is the road in meters?
在一段公路的两边每隔6米种一棵树，共种了180棵，如果两端都种上树，这段公路长多少米．
<gadget id="calculator">180 / 2</gadget>
<output>90</output>

<gadget id="calculator">90 - 1</gadget>
<output>89</output>

<gadget id="calculator">89 * 6</gadget>
<output>534</output>

<result>534</result>