On both sides of a 100-meter-long road, plant a tree every 5 meters (both ends must be planted), how many trees can be planted in total.
在一条长100米的路两旁，每隔5米栽一棵树(两端都要栽)，一共可以栽多少棵树．
<gadget id="calculator">100 / 5</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>