The school plants trees on both sides of a path with a length of 100 meters, one tree every 5 meters (both ends are planted), how many trees can be planted in total.
学校在长为100米的小路两边栽树，每隔5米种一棵(两端都栽)，一共可以栽多少棵．
<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>