Plant trees on both sides of a path with a length of 180 meters (both ends are planted), and plant one tree every 20 meters. How many trees will be planted in total?
在一条长为180米的小路两旁植树(两端都植)，每20米栽一棵．一共需要栽多少棵树？
<gadget id="calculator">180 / 20</gadget>
<output>9</output>

<gadget id="calculator">9 + 1</gadget>
<output>10</output>

<gadget id="calculator">10 * 2</gadget>
<output>20</output>

<result>20</result>