Plant trees between two buildings 120 meters apart, and plant one tree every 20 meters. How many trees are planted in total? (think about the actual situation)
在相距120米的两楼之间种树，每隔20米栽一棵，共栽多少棵．(想想实际情况)
<gadget id="calculator">120 / 20</gadget>
<output>6</output>

<gadget id="calculator">6 - 1</gadget>
<output>5</output>

<result>5</result>