Plant trees equidistantly along a 360-meter-long embankment (trees should be planted at both ends). How many holes do you need to dig to plant a tree every 6 meters after you have dug a hole for planting a tree every 4 meters?
一条长360米的河堤边等距离植树(两端都要植树)．已挖好每隔4米植一棵树的坑后要改成每隔6米植一棵树，还要挖多少个坑．
<gadget id="calculator">360 / 6</gadget>
<output>60</output>

<gadget id="calculator">60 + 1</gadget>
<output>61</output>

<gadget id="calculator">360 / 12</gadget>
<output>30</output>

<gadget id="calculator">30 + 1</gadget>
<output>31</output>

<gadget id="calculator">61 - 31</gadget>
<output>30</output>

<result>30</result>