The garden workers planted a tree every 5 meters on both sides of the 60-meter-long path (both ends are planted), and now it is changed to plant a tree every 4 meters, so how many trees do not need to be transplanted?
园林工人在长60米的小路两边每隔5米栽一棵树(首尾都栽)，现在要改成每隔4米栽一棵树，那么不用移栽的树有多少棵？
<gadget id="calculator">4 * 5</gadget>
<output>20</output>

<gadget id="calculator">60 / 20</gadget>
<output>3</output>

<gadget id="calculator">3 + 1</gadget>
<output>4</output>

<result>4</result>