Uncle Wang planted a tree every 4 meters on both sides of the 240-meter road (both ends are planted). Now it is changed to plant a tree every 6 meters. So, how many trees do not need to be transplanted?
王大爷在240米的公路两边每隔4米栽一棵树(首尾都栽)，现在要改成每隔6米栽一棵树，那么，不用移栽的树有多少棵？
<gadget id="calculator">240 / 12</gadget>
<output>20</output>

<gadget id="calculator">20 + 1</gadget>
<output>21</output>

<gadget id="calculator">21 * 2</gadget>
<output>42</output>

<result>42</result>