Plant trees on both sides of a road, plant a tree every 3 meters, and there are still 5 saplings left from the east end of the road to the west end. How many meters long.
在一条公路的两边植树，每隔3米种一棵树，从公路的东头种到西头还剩5棵树苗，如果改为4米种一棵，还剩树苗115棵，则这条公路长多少米．
<gadget id="calculator">115 - 2 - 5</gadget>
<output>108</output>

<gadget id="calculator">2 + 108</gadget>
<output>110</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">2 * (1/3)</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">2 * (1/4)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">(2/3) - (1/2)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">110 / (1/6)</gadget>
<output>660</output>

<result>660</result>