A small road with a length of 80 meters is planned to plant sycamore trees on both sides of the road, one tree every 4 meters (trees are also planted at both ends), how many trees can be planted in total?
一条长80米的小路，准备在路的两侧栽种梧桐树，每4米栽一棵(两端也栽树)，一共可以栽树多少棵？
<gadget id="calculator">80 / 4</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>